Diagnosis of Internal Disorders and When to Refer

A large share of the patients who walk into a chiropractic office with back, neck, chest wall or shoulder pain have a perfectly mechanical problem, but a small and important minority have disease in the heart, lungs, gut, kidneys, blood or glands that is projecting pain onto the musculoskeletal system. The General Diagnosis domain of Part II tests whether you can recognize those patients from the history, vital signs, physical exam and basic labs, and whether you know how fast they need to be sent elsewhere. This chapter walks through the internal disorders the board returns to most often and threads a clear referral decision through every one of them.

Section 1ENT, respiratory and cardiovascular disorders

The upper airway: sinusitis and pharyngitis

Acute rhinosinusitis is overwhelmingly viral. It produces nasal congestion, purulent discharge, facial pressure that worsens on bending forward, and tenderness over the maxillary or frontal sinuses. Transillumination of a fluid filled maxillary or frontal sinus shows reduced light transmission compared with the opposite side. A bacterial cause becomes likely when symptoms persist beyond 10 days without improvement, when the illness is severe from the start (fever of 39°C or more with purulent discharge for three or four days), or when the patient improves and then worsens again ("double sickening"). Chronic sinusitis lasts 12 weeks or more. The danger of sinusitis is local spread: periorbital swelling, painful or limited eye movement, visual change, severe headache with neck stiffness, or altered mental status suggests orbital cellulitis, meningitis or cavernous sinus thrombosis, and needs emergency care.

Pharyngitis is also mostly viral. The board question is whether it could be group A beta hemolytic streptococcus (Streptococcus pyogenes). The Centor criteria award one point each for fever, tonsillar exudate, tender anterior cervical lymphadenopathy and absence of cough; the McIsaac modification adds a point for age 3 to 14 and subtracts one for age 45 or older. Higher scores justify a rapid antigen test or culture. Untreated strep can lead to acute rheumatic fever (migratory polyarthritis, carditis, Sydenham chorea, erythema marginatum, subcutaneous nodules) and poststreptococcal glomerulonephritis (cola colored urine, edema, hypertension). Antibiotics prevent rheumatic fever but not glomerulonephritis.

Infectious mononucleosis (Epstein Barr virus) causes sore throat, fever, marked fatigue and posterior cervical lymphadenopathy in adolescents and young adults, with splenomegaly in about half. The heterophile antibody (Monospot) test confirms it, and atypical lymphocytes appear on the smear. Contact sports and forceful abdominal or thoracic manipulation are avoided for at least three to four weeks because the enlarged spleen can rupture; left upper quadrant pain referred to the left shoulder (Kehr sign) in such a patient is an emergency. Two upper airway emergencies deserve memorizing: peritonsillar abscess (severe unilateral throat pain, "hot potato" muffled voice, trismus, uvula deviated away from the swollen side) and epiglottitis (rapid onset, drooling, inability to swallow, inspiratory stridor, tripod posture). Never examine the throat of a child you suspect has epiglottitis; call emergency services.

Obstructive lung disease: asthma and COPD

Asthma is chronic airway inflammation with reversible bronchoconstriction and airway hyperresponsiveness. Symptoms are episodic wheeze, chest tightness, dyspnea and cough (often at night or early morning) triggered by allergens, exercise, cold air, infections, smoke, aspirin or beta blockers. Spirometry shows obstruction (reduced FEV1/FVC) that improves by at least 12 percent and 200 mL in FEV1 after a bronchodilator. A severe attack shows use of accessory muscles, inability to speak in full sentences, pulsus paradoxus, tachycardia and falling peak flow. A "silent chest" (no wheeze because almost no air is moving), cyanosis, confusion or exhaustion signals impending respiratory failure and needs emergency services.

Chronic obstructive pulmonary disease is persistent, largely irreversible airflow limitation, diagnosed when the post bronchodilator FEV1/FVC is below 0.70. Cigarette smoking is the main cause. Chronic bronchitis is defined clinically as a productive cough for at least three months in each of two consecutive years; patients are classically hypoxemic, cyanotic and edematous from cor pulmonale ("blue bloaters"). Emphysema is destruction of alveolar walls with loss of elastic recoil; patients are thin, tachypneic, breathe through pursed lips, have a barrel chest with increased AP diameter, hyperresonant percussion, decreased breath sounds and a low flat diaphragm on chest film ("pink puffers"). Centriacinar emphysema with upper lobe predominance is typical of smoking; panacinar emphysema in the lower lobes of a young nonsmoker suggests alpha 1 antitrypsin deficiency, which can also cause liver disease.

Pneumonia, effusion, pneumothorax and pulmonary embolism

Community acquired pneumonia presents with fever, chills, cough with sputum, pleuritic chest pain and dyspnea. Over a lobar consolidation the exam finds dullness, increased tactile fremitus, bronchial breath sounds, crackles, egophony (spoken "E" heard as "A"), bronchophony and whispered pectoriloquy, because solid lung transmits sound better than air filled lung. Streptococcus pneumoniae is the most common bacterial cause (rusty sputum, lobar pattern); Mycoplasma pneumoniae causes "walking" atypical pneumonia in young adults; Klebsiella causes currant jelly sputum in alcoholics; Legionella is linked to contaminated water systems, with diarrhea and hyponatremia. The CURB 65 score (Confusion, Urea over 7 mmol/L, Respiratory rate 30 or more, Blood pressure under 90 systolic or 60 diastolic, age 65 or older) estimates severity; a score of 2 or more generally means hospital care.

Spontaneous pneumothorax classically strikes a tall, thin young man (rupture of an apical bleb) with sudden unilateral pleuritic chest pain and dyspnea. Tension pneumothorax (hypotension, distended neck veins, tracheal shift away from the affected side) is immediately life threatening.

Pulmonary embolism usually arises from a deep vein thrombosis of the leg or pelvis. Risk follows Virchow triad: venous stasis (immobility, long travel, recent surgery, casting), hypercoagulability (malignancy, pregnancy, estrogen therapy, inherited thrombophilia such as factor V Leiden) and endothelial injury. The typical picture is sudden dyspnea, pleuritic chest pain, tachycardia, tachypnea, sometimes hemoptysis or syncope, often with a swollen, tender calf. The Wells score estimates pretest probability; a negative D dimer helps exclude PE in low risk patients, and CT pulmonary angiography confirms it. The Homans sign (calf pain on passive dorsiflexion) is neither sensitive nor specific and should not be used to rule DVT in or out. Suspected PE is an emergency. Suspected DVT without chest symptoms needs same day evaluation with duplex ultrasound, and the affected limb should not be massaged.

Hypertension

Blood pressure is measured after five minutes of seated rest, back supported, feet flat, arm supported at heart level, with a cuff whose bladder encircles about 80 percent of the arm. A cuff that is too small overestimates the reading. Diagnosis rests on the average of at least two readings on at least two occasions, ideally confirmed by home or ambulatory monitoring to exclude white coat hypertension.

About 90 percent of hypertension is primary (essential). Suspect a secondary cause when hypertension begins before age 30 or after 55, is resistant to three drugs, or comes with clues: an abdominal bruit and rising creatinine with ACE inhibitors (renal artery stenosis, fibromuscular dysplasia in young women, atherosclerosis in older adults); episodic headache, sweating and palpitations (pheochromocytoma); hypokalemia (primary aldosteronism); moon face and striae (Cushing syndrome); loud snoring and daytime sleepiness (obstructive sleep apnea); or higher pressure in the arms than the legs with delayed femoral pulses and rib notching on chest film (coarctation of the aorta). Long standing hypertension damages target organs: left ventricular hypertrophy, heart failure, stroke, chronic kidney disease, retinopathy (arteriolar narrowing, AV nicking, flame hemorrhages, cotton wool spots, and papilledema in severe disease).

A reading in the crisis range with no signs of acute organ damage is called hypertensive urgency and needs prompt (same day) medical contact. The same reading with chest pain, dyspnea, neurological deficit, confusion, severe headache, visual loss or papilledema is a hypertensive emergency and requires emergency services. Do not perform high velocity manipulation on a patient in the crisis range.

Coronary artery disease and heart failure

Stable angina is predictable substernal pressure, squeezing or tightness provoked by exertion, cold or emotion, lasting a few minutes and relieved by rest or nitroglycerin. It may radiate to the left arm, jaw, neck, epigastrium or between the shoulder blades. A patient who clenches a fist over the sternum to describe the pain (Levine sign) is describing ischemia. Acute coronary syndrome includes unstable angina (new onset, at rest, or a crescendo pattern), non ST elevation MI and ST elevation MI. Myocardial infarction pain typically lasts more than 20 minutes, is not relieved by rest, and comes with diaphoresis, nausea, dyspnea and a sense of doom. Women, diabetics and older adults more often have atypical presentations: fatigue, dyspnea, nausea, epigastric discomfort or isolated jaw, arm or upper back pain. Diagnosis rests on the ECG and cardiac troponin. Any suspected acute coronary syndrome means calling emergency services; the patient should not drive.

Chest wall pain from a costochondral or costovertebral problem is reproduced by palpation or a specific movement, is sharp and localized, and is unrelated to exertion. Costochondritis (tender costochondral junctions without swelling) and Tietze syndrome (tender, swollen upper costal cartilage) are common benign causes. Reproducible tenderness lowers, but never eliminates, the probability of a cardiac cause; if the history sounds ischemic, refer regardless.

Heart failure means the heart cannot pump enough blood to meet demand at normal filling pressures. Left sided failure backs fluid into the lungs: exertional dyspnea, orthopnea (needs more pillows), paroxysmal nocturnal dyspnea, basilar crackles, an S3 gallop and a displaced apical impulse. Right sided failure, most often caused by left sided failure, backs fluid into the systemic veins: jugular venous distension, positive hepatojugular reflux, hepatomegaly, ascites and bilateral dependent pitting edema. The New York Heart Association classes describe function: I, no limitation; II, symptoms with ordinary activity; III, symptoms with less than ordinary activity; IV, symptoms at rest. BNP (B type natriuretic peptide) is elevated.

Aortic aneurysm and dissection

An abdominal aortic aneurysm (AAA) is an infrarenal aorta dilated to 3 cm or more. Risk factors are age over 65, male sex, smoking (the strongest modifiable factor), hypertension, atherosclerosis and a family history. Most are asymptomatic and are found as a pulsatile, expansile midline mass above the umbilicus, on ultrasound, or as curvilinear calcification anterior to the lumbar spine on a lateral lumbar radiograph. A one time screening ultrasound is recommended for men aged 65 to 75 who have ever smoked. Rupture risk climbs steeply above 5.5 cm, the usual threshold for repair, and with rapid growth. An expanding or leaking aneurysm causes deep, boring low back, flank or abdominal pain that does not change with position; frank rupture produces the triad of severe pain, hypotension and a pulsatile mass. A patient with a known AAA and new back pain is sent to the emergency department, and deep abdominal palpation and lumbar manipulation are avoided in anyone with a known aneurysm larger than about 4 cm unless cleared by the vascular team.

Aortic dissection is a tear in the intima that lets blood split the media and form a false lumen. The pain is sudden, maximal at onset, and described as tearing or ripping, felt in the anterior chest (ascending) or the interscapular back (descending), sometimes migrating as the dissection extends. Clues are a difference of more than 20 mmHg in systolic pressure between the arms, pulse deficits, a new aortic regurgitation murmur, stroke symptoms and a widened mediastinum on chest film. Risk factors are chronic hypertension (most common), Marfan and Ehlers Danlos syndromes, bicuspid aortic valve, cocaine use, pregnancy and prior cardiac surgery. The Stanford classification drives treatment (Figure 3.1).

Peripheral arterial disease

Peripheral arterial disease (PAD) is atherosclerotic narrowing of the leg arteries, strongly linked to smoking and diabetes. Its hallmark is intermittent claudication: reproducible cramping or aching in the calf (or thigh and buttock with aortoiliac disease) brought on by a predictable walking distance and relieved within a few minutes by simply standing still. Signs include diminished or absent pedal pulses, cool shiny hairless skin, thickened nails, delayed capillary refill, pallor on elevation and dependent rubor. The ankle brachial index (ABI) divides ankle systolic pressure by the higher arm systolic pressure: 1.0 to 1.4 is normal, 0.90 or less confirms PAD, under about 0.4 indicates severe disease, and over 1.4 means calcified, noncompressible vessels (often diabetes) that make the test unreliable. Critical limb ischemia causes rest pain in the forefoot at night that is eased by hanging the leg over the bed, plus ulcers or gangrene. Acute limb ischemia from embolism shows the six Ps: pain, pallor, pulselessness, paresthesia, paralysis and poikilothermia (a cold limb), and is an emergency.

Section 2Blood, lymphatic and immunological disorders

Anemia

Anemia is a hemoglobin below about 13.5 g/dL in men and 12 g/dL in women. Symptoms reflect reduced oxygen delivery and its compensation: fatigue, exertional dyspnea, palpitations, headache, pallor of the conjunctivae and palmar creases, tachycardia and a soft flow murmur. The first laboratory step is the mean corpuscular volume (MCV), which sorts anemia into three groups (Figure 3.2).

Iron deficiency anemia is the most common anemia worldwide. In a menstruating woman it usually reflects menstrual loss, but in a man or a postmenopausal woman it is presumed to be gastrointestinal blood loss (including colon cancer) until proven otherwise, and needs referral for evaluation. Signs include koilonychia (spoon nails), angular cheilitis, glossitis and pica (craving ice or clay). Ferritin is low, total iron binding capacity is high and the smear shows small pale (microcytic, hypochromic) cells. Thalassemias produce microcytosis with normal or high iron; severe beta thalassemia causes marrow expansion with a "hair on end" skull and widened medullary spaces.

Vitamin B12 deficiency is classically due to pernicious anemia (autoantibodies against intrinsic factor or parietal cells), but also follows gastrectomy, ileal resection or Crohn disease, a strict vegan diet, and long term metformin or acid suppression. It causes megaloblastic anemia with hypersegmented neutrophils and, importantly, subacute combined degeneration of the dorsal columns (loss of vibration and position sense, positive Romberg) and lateral corticospinal tracts (weakness, spasticity, upgoing toes), plus peripheral neuropathy and cognitive change. The neurological damage can occur without anemia and becomes permanent if treatment is delayed. Methylmalonic acid and homocysteine are both raised in B12 deficiency; in folate deficiency only homocysteine rises and there are no neurological findings. Giving folate alone to a B12 deficient patient can correct the blood picture while the neuropathy progresses.

Sickle cell disease (autosomal recessive, glutamic acid replaced by valine at position 6 of beta globin) causes chronic hemolysis and painful vaso occlusive crises. Bone infarcts produce H shaped ("Lincoln log") vertebrae from central endplate depression, avascular necrosis of the femoral and humeral heads, and dactylitis in children. Patients are prone to Salmonella osteomyelitis because of autosplenectomy, although Staphylococcus aureus is still common.

Leukemias, lymphomas and multiple myeloma

Leukemias replace the marrow with malignant cells, causing the triad of marrow failure: anemia (fatigue, pallor), neutropenia (fevers and infections) and thrombocytopenia (petechiae, bruising, bleeding gums), often with bone pain from marrow expansion. Lymphomas are malignancies of lymphoid tissue that usually present as painless lymphadenopathy, sometimes with B symptoms: fever, drenching night sweats and unintended weight loss of more than 10 percent of body weight in six months.

Multiple myeloma is the most common primary malignant tumor of bone in adults and a favorite board topic because it presents as back pain. The mnemonic CRAB captures its damage: hyperCalcemia, Renal failure (light chains clog the tubules), Anemia and Bone lesions. The pain is deep, persistent and present at rest and at night, often in an older adult with fatigue, recurrent infections and an unexplained very high ESR. Radiographs show multiple punched out lytic lesions (the "raindrop" skull), diffuse osteopenia and vertebral compression fractures; the vertebral pedicles are often spared early, unlike metastatic carcinoma, which tends to destroy the pedicle (the "winking owl" sign on an AP film). Because myeloma lesions are purely lytic with little osteoblastic response, a bone scan is often normal (cold); a skeletal survey, low dose whole body CT, or MRI is used instead. Serum and urine protein electrophoresis show the monoclonal protein.

Bleeding and clotting disorders

The pattern of bleeding tells you where the defect is. Platelet disorders (thrombocytopenia, platelet dysfunction from aspirin or uremia, von Willebrand disease) cause mucocutaneous bleeding: petechiae, purpura, nosebleeds, gum bleeding, heavy menses and prolonged oozing from cuts. Coagulation factor disorders (hemophilia, liver disease, vitamin K deficiency, anticoagulant drugs) cause deep bleeding: hemarthroses, muscle hematomas and delayed bleeding after trauma or surgery. Hemophilia A (factor VIII) and hemophilia B (factor IX) are X linked recessive, so they affect males; recurrent knee, ankle and elbow hemarthroses lead to hemophilic arthropathy with widened intercondylar notch and squared patella on radiographs. Von Willebrand disease is the most common inherited bleeding disorder.

Patients taking warfarin (monitored by INR, therapeutic range usually 2 to 3) or direct oral anticoagulants (apixaban, rivaroxaban, dabigatran) bruise and bleed more easily, and anticoagulation is a recognized risk factor for spinal epidural hematoma. Forceful soft tissue work and high velocity thrust are modified or avoided in anticoagulated patients and in those with severe thrombocytopenia or hemophilia. New back pain with rapidly developing leg weakness in an anticoagulated patient is an emergency.

Lymphadenopathy

Most enlarged lymph nodes are reactive to a nearby infection: they are tender, soft, mobile and smaller than about 1 cm, and they shrink within a few weeks. Features that raise concern for malignancy are hard, rubbery or matted nodes fixed to surrounding tissue, size over about 1.5 to 2 cm, painless and progressive growth, persistence beyond four to six weeks, generalized lymphadenopathy, age over 40, B symptoms, and above all a supraclavicular location. A left supraclavicular node (Virchow node, Troisier sign) suggests metastatic abdominal cancer, especially gastric; a right supraclavicular node drains the mediastinum, lungs and esophagus. Painless, firm axillary nodes in a woman call for breast evaluation. A suspicious node is referred for medical evaluation within days to a couple of weeks, sooner if B symptoms are present.

Immunodeficiency and autoimmune disease

Immunodeficiency is most often secondary: HIV infection, long term glucocorticoids, chemotherapy, biologic drugs (TNF inhibitors), transplant medication, poorly controlled diabetes, malnutrition, chronic kidney disease, splenectomy and advanced age. In HIV, a CD4 count below 200 cells per µL (or an AIDS defining illness) defines AIDS; opportunistic infections and lymphoma follow. For the chiropractor the key point is that an immunosuppressed patient with new spinal pain has a much higher risk of vertebral osteomyelitis, discitis and epidural abscess, often with little or no fever, and a lower threshold for imaging and referral.

Autoimmune diseases share fatigue, low grade fever, arthralgia, raised ESR and CRP, and specific autoantibodies.

Section 3Gastrointestinal and genitourinary disorders

Visceral pain and referral to the back

Visceral afferents travel with sympathetic nerves into the same spinal segments that supply skin and muscle, so pain from an organ is felt in the dermatomes and myotomes of its segmental supply (convergence projection). Visceral pain is deep, diffuse and poorly localized, and is often accompanied by nausea, sweating or pallor. Its defining feature for the chiropractor is that it is not changed by spinal movement, posture or palpation, but it does change with organ function: eating, swallowing, bowel movements, urination, menstruation or exertion. Pain that wakes the patient, constant pain unrelieved by any position, and pain with fever, weight loss, jaundice, blood in urine or stool, or changes in bowel and bladder habit point to a visceral source (Figure 3.3).

Upper gastrointestinal tract

Gastroesophageal reflux disease causes heartburn and regurgitation after meals, on bending and lying flat, and may cause chronic cough, hoarseness or noncardiac chest pain. Alarm features that require endoscopy referral are dysphagia, odynophagia, weight loss, GI bleeding or anemia, persistent vomiting and new symptoms after about age 60. Long standing reflux can cause Barrett esophagus (columnar metaplasia), the precursor of esophageal adenocarcinoma.

Peptic ulcer disease is caused mainly by Helicobacter pylori and NSAIDs. Duodenal ulcer pain classically improves with food and returns two to three hours later or at night; gastric ulcer pain is worse with eating and causes weight loss. A posterior duodenal ulcer can penetrate the pancreas and present as mid back pain. Complications are bleeding (hematemesis, coffee ground vomitus, black tarry melena), perforation (sudden severe epigastric pain, board like abdomen, free air under the diaphragm on an upright chest film) and gastric outlet obstruction.

Gallstone disease favors women, obesity, age over 40, pregnancy and rapid weight loss. Biliary colic is steady right upper quadrant or epigastric pain after a fatty meal, lasting under about six hours and referring to the inferior angle of the right scapula. Acute cholecystitis adds fever, persistent pain and a positive Murphy sign (the patient stops inspiring when the examiner presses under the right costal margin). A stone in the common bile duct causes jaundice; ascending cholangitis causes the Charcot triad of fever, right upper quadrant pain and jaundice, and adding hypotension and confusion gives the Reynolds pentad. Ultrasound is the first imaging test.

Acute pancreatitis is caused mostly by gallstones and alcohol, also by very high triglycerides, hypercalcemia and certain drugs. Severe epigastric pain bores through to the back, is eased by sitting up and leaning forward, and comes with nausea and vomiting. Lipase over three times normal confirms it. Flank ecchymosis (Grey Turner sign) and periumbilical ecchymosis (Cullen sign) mark hemorrhagic disease. Pancreatic cancer causes dull epigastric and mid back pain, weight loss, new onset diabetes and painless jaundice with a palpable nontender gallbladder (Courvoisier sign) when it arises in the head.

Lower gastrointestinal tract and liver

Appendicitis begins as vague periumbilical pain (visceral, T10) with anorexia and nausea, then shifts to the right lower quadrant as the parietal peritoneum becomes inflamed, with maximal tenderness at McBurney point (one third of the way from the ASIS to the umbilicus). Supporting signs are rebound tenderness, Rovsing sign (pressing the left lower quadrant hurts the right), the psoas sign (pain on passive hip extension or resisted hip flexion, a retrocecal appendix irritating the right psoas) and the obturator sign (pain on internal rotation of the flexed right hip, a pelvic appendix). A positive psoas sign can mimic a lumbar or hip problem. Suspected appendicitis is an emergency referral. Diverticulitis is the older adult's equivalent on the left: left lower quadrant pain, fever and change in bowel habit.

Both forms of inflammatory bowel disease cause enteropathic arthritis: a peripheral arthritis that tracks bowel activity, and an axial spondyloarthritis (sacroiliitis, spondylitis) that is linked to HLA B27 and runs independently of the bowel. Young adults with inflammatory back pain plus chronic diarrhea, weight loss or blood in the stool need gastroenterology referral. Irritable bowel syndrome, in contrast, is recurrent abdominal pain related to defecation with altered stool form or frequency and no alarm features (no bleeding, anemia, weight loss, nocturnal symptoms or onset after 50).

Viral hepatitis causes malaise, anorexia, right upper quadrant discomfort, jaundice, dark urine and pale stools, with transaminases (ALT more than AST) in the hundreds or thousands. Hepatitis A and E spread by the fecal oral route and do not become chronic (E is dangerous in pregnancy). Hepatitis B spreads by blood, sex and birth; HBsAg means current infection, anti HBs means immunity (vaccination or recovery), and IgM anti HBc marks acute infection. Hepatitis C spreads mainly by blood (injection drug use), becomes chronic in most patients and is now curable with antivirals. Chronic hepatitis and alcohol lead to cirrhosis: spider angiomas, palmar erythema, gynecomastia, ascites, caput medusae, asterixis and an AST to ALT ratio over 2 in alcoholic disease.

Kidney, urinary tract and prostate

Nephrolithiasis: most stones are calcium oxalate and radiopaque; struvite (magnesium ammonium phosphate) stones form staghorn calculi with urease producing organisms such as Proteus; uric acid stones are radiolucent on plain film. Renal colic is severe, colicky flank pain radiating to the groin, testicle or labia, with nausea and hematuria. The patient writhes and cannot find a comfortable position, unlike the patient with mechanical back pain who lies still. Noncontrast CT is the standard test; stones under about 5 mm usually pass. An obstructed, infected kidney (fever plus a stone) is an emergency.

Lower urinary tract infection (cystitis) causes dysuria, frequency, urgency and suprapubic pain without fever; E. coli is the usual organism. Pyelonephritis adds fever, chills, flank pain, costovertebral angle tenderness (pain when the examiner strikes the angle between the 12th rib and the spine, sometimes called the Murphy punch test) and white cell casts in the urine; it needs same day medical care, and emergency care if the patient is septic, vomiting or pregnant.

Acute kidney injury is classified as prerenal (low perfusion, BUN to creatinine ratio over 20), intrinsic (acute tubular necrosis, glomerulonephritis, drugs) and postrenal (obstruction, often prostatic). Chronic kidney disease is a GFR under 60 mL/min/1.73 m² or kidney damage for three months or more, caused mainly by diabetes and hypertension. It brings anemia (low erythropoietin), hypertension, edema, metabolic acidosis, hyperkalemia and renal osteodystrophy (secondary hyperparathyroidism, osteomalacia, the "rugger jersey" spine of banded endplate sclerosis). NSAIDs should be avoided.

Benign prostatic hyperplasia arises in the transition zone and causes lower urinary tract symptoms: hesitancy, weak stream, dribbling, frequency, nocturia and incomplete emptying, sometimes acute retention. Prostate cancer arises mostly in the peripheral zone, felt as a hard, irregular nodule on digital rectal exam, and is often asymptomatic until it spreads. It metastasizes to the lumbar spine, pelvis and proximal femurs through the valveless vertebral venous system (Batson plexus), producing osteoblastic (sclerotic) lesions, including the "ivory vertebra." Back pain in an older man with urinary symptoms, weight loss or a known raised PSA is referred promptly.

Section 4Endocrine, metabolic and nutritional disorders

Diabetes mellitus

Type 1 diabetes is autoimmune destruction of beta cells, usually in youth, and presents with polyuria, polydipsia, weight loss and sometimes diabetic ketoacidosis (Kussmaul breathing, fruity breath, abdominal pain, dehydration). Type 2 diabetes is insulin resistance with relative insulin deficiency, linked to obesity and inactivity, and is often found on screening. Diagnosis requires a fasting glucose of 126 mg/dL or more, an HbA1c of 6.5 percent or more, a 2 hour oral glucose tolerance value of 200 mg/dL or more, or a random glucose of 200 or more with classic symptoms. Prediabetes is a fasting glucose of 100 to 125 or an HbA1c of 5.7 to 6.4 percent. Complications are microvascular (retinopathy, nephropathy, stocking and glove peripheral neuropathy) and macrovascular (coronary, cerebral and peripheral arterial disease). Musculoskeletal associations include adhesive capsulitis, carpal tunnel syndrome, Dupuytren contracture, DISH, Charcot (neuropathic) joints of the foot and diabetic amyotrophy (painful proximal thigh weakness). Hypoglycemia in the office (sweating, tremor, palpitations, hunger, confusion) in a patient on insulin or a sulfonylurea is treated with about 15 g of fast sugar if the patient can swallow, and with emergency services if not.

Thyroid, parathyroid and adrenal disorders

Osteoporosis, obesity and metabolic syndrome

Osteoporosis is low bone mass with microarchitectural deterioration and fragility fractures. On DEXA, a T score of minus 2.5 or lower (compared with a young adult reference) is osteoporosis; minus 1.0 to minus 2.5 is osteopenia (low bone mass). The Z score (compared with age matched peers) is used for premenopausal women, men under 50 and children; a low Z score prompts a search for secondary causes. A fragility fracture of the spine or hip establishes the diagnosis regardless of T score. Risk factors are female sex, older age, white or Asian ancestry, low body weight, early menopause, smoking, excess alcohol, inactivity, a parental hip fracture, long term glucocorticoids, hyperthyroidism, hyperparathyroidism, malabsorption and rheumatoid arthritis. FRAX estimates ten year fracture risk. Women 65 and older are screened. Vertebral compression fractures are the most common osteoporotic fracture and cause thoracic kyphosis and height loss; sudden thoracolumbar pain after a minor strain in an older woman is a fracture until proven otherwise. Thrust force is reduced or replaced by low force methods in osteoporotic patients. Osteomalacia (defective mineralization from vitamin D deficiency) differs by causing diffuse bone pain, proximal weakness, low or normal calcium and phosphate, high alkaline phosphatase and Looser zones (pseudofractures).

Body mass index of 25 to 29.9 is overweight and 30 or more is obesity. Metabolic syndrome is diagnosed when three of five criteria are met: waist over 40 inches (102 cm) in men or 35 inches (88 cm) in women; triglycerides 150 mg/dL or more; HDL under 40 in men or under 50 in women; blood pressure 130/85 or higher; fasting glucose 100 or higher.

Vitamin deficiencies

Section 5Infectious disease and the red flag approach

Infections a chiropractor must recognize

Fever, fever of unknown origin and sepsis

A fever is generally a temperature of 38.0°C (100.4°F) or higher. Normal adult vital signs are a heart rate of 60 to 100, respiratory rate of 12 to 20, and oxygen saturation of 95 percent or more. Fever of unknown origin is, in the classic definition, a temperature of 38.3°C (101°F) or higher on several occasions over more than three weeks that remains undiagnosed after a reasonable workup. Its causes fall into infection (endocarditis, tuberculosis, abscess, osteomyelitis), malignancy (lymphoma, leukemia, renal cell carcinoma), noninfectious inflammatory disease (giant cell arteritis, adult Still disease, lupus) and miscellaneous causes (drug fever, thromboembolism). FUO is always a medical referral.

Sepsis is life threatening organ dysfunction caused by a dysregulated response to infection. At the bedside, the quick SOFA score flags risk when two of three are present: respiratory rate of 22 or more, altered mentation, and systolic pressure of 100 mmHg or less. The older SIRS criteria are temperature over 38°C or under 36°C, heart rate over 90, respiratory rate over 20 and white cell count over 12,000 or under 4,000. An infected patient who is confused, breathing fast, hypotensive, mottled or not passing urine is septic until proven otherwise and needs emergency services; elderly and immunosuppressed patients may be hypothermic rather than febrile.

Red flags and urgency of referral

Individually most have modest accuracy; their value lies in clusters and in the clinician's willingness to act on them.

Co-management means that the chiropractor and the medical provider share care, each within scope, with clear communication. A good referral letter states the patient's identifying data, the reason for referral, the relevant history, exam and imaging findings, your working impression, the specific question you want answered, and whether you plan to continue care. Document the referral, the patient's response (including refusal, with the risks explained) and the follow up. In an emergency, phone first and send the paperwork afterwards; never let a patient with suspected MI, stroke or dissection drive themselves.

Words worth knowing