Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (63 page)

   Common essential hypertension risk factors are family history (2× risk), African descent, obesity, excessive alcohol or salt intake, physical inactivity, dyslipidemia, and personality traits of depression, time urgency/impatience.

   Secondary hypertension should be considered for severe or resistant hypertension (high BP despite treatment from three medications in different classes including diuretic), an acute rise in previously stable BP, <30 years old nonblack patients with no family history, malignant hypertension, or findings from screening data.

   If secondary hypertension is suggested, a number of conditions need to be considered including primary renal disease, renovascular disease, sleep apnea, coarctation of the aorta (young children), pheochromocytoma, primary aldosteronism, oral contraceptive use, and thyroid and parathyroid disease.

   Malignant hypertension is associated with neurologic symptoms due to intracerebral or subarachnoid bleeding (headache, nausea, vomiting, somnolence, confusion, seizures, coma) and/or visual disturbance (retinal hemorrhages and exudates or papilledema).

   Laboratory Findings

   Most patients with presumed primary (essential) hypertension should undergo a limited evaluation due to poor diagnostic yield and high likelihood of false positive results.

   
Core laboratory:
hematocrit, urinalysis, routine blood chemistries, GFR, lipid profile and ECG (assess for LVH). Urine microalbumin or echocardiography could be considered.

   Considerations:

   When hypertension is associated with decreased serum potassium, rule out antihypertensive medication, Cushing syndrome, primary aldosteronism (also with slight hypernatremia), and diuretic administration. Consider plasma aldosterone to renin ratio (also elevated in obesity).

   Increased calcium is seen with hyperparathyroidism. Vascular reactivity and day–night blood pressure regulation play a role in hypertensive response.

   Laboratory findings due to administration of some antihypertensive drugs, such as

   Oral diuretics (e.g., benzothiadiazines): hyperuricemia, hypokalemia, or hyperglycemia or aggravation of preexisting DM; less commonly, bone marrow depression, aggravation of renal or hepatic insufficiency, cholestatic hepatitis, or toxic pancreatitis.