A Branching Algorithm
© 2019 Society of Hospital Medicine
Laboratory studies revealed a white blood cell count of 13.3 × 103/uL with a normal differential, hemoglobin 13.9 g/dL, platelet count 373 × 103/uL, sodium 142 mmol/L, potassium 3.8 mmol/L, chloride 103 mmol/L,bicarbonate 25 mmol/L, blood urea nitrogen 12 mg/dL, creatinine 1.3 mg/dL (a baseline creatinine level was not available), glucose 88 mg/dL, calcium 10.6 mg/dL, albumin 4.9 g/dL, aspartate aminotransferase 27 IU/L, alanine aminotransferase 37 IU/L, and lipase 40 IU/L. Urinalysis revealed 5-10 white blood cells per high power field without casts and 10 mg/dL protein. Urine toxicology was not performed. Electrocardiogram (ECG) showed left ventricular hypertrophy (LVH). Chest radiography was normal.
The abdominal examination does not suggest peritonitis. The laboratory tests do not suggest inflammation of the liver, pancreas, or biliary tree as the cause of his abdominal pain or diarrhea. The murmur may indicate hypertrophic cardiomyopathy or a congenital anomaly such as bicuspid aortic valve; but neither would explain hypertension unless they were associated with another developmental abnormality, such as coarctation of the aorta. Tricuspid regurgitation is conceivable and if confirmed, might raise concern for carcinoid syndrome, which can cause diarrhea. The normal neurologic examination, including the absence of papilledema, lowers suspicion of intracranial hemorrhage as a cause of his headache.
The albumin of 4.9 g/dL likely reflects hypovolemia resulting from vomiting and diarrhea. Vasoconstriction associated with pheochromocytoma can cause pressure diuresis and resultant hypovolemia. Hyperaldosteronism arising from bilateral adrenal hyperplasia or adrenal adenoma commonly causes hypokalemia, although this is not a universal feature.
The duration of his mildly decreased glomerular filtration rate is uncertain. He may have chronic kidney disease from sustained hypertension, or acute kidney injury from hypovolemia. The mild pyuria could indicate infection or renal calculi, either of which could account for generalized abdominal pain or could reflect an acute renal injury from acute interstitial nephritis from his proton pump inhibitor or hydrochlorothiazide.
LVH on the ECG indicates longstanding hypertension. The chest radiograph does not reveal clues to the etiology of or sequelae from hypertension. In particular, there is no widened aorta to suggest aortic dissection, no pulmonary edema to indicate heart failure, and no rib notching that points toward aortic coarctation. A transthoracic echocardiogram to assess for valvular and other structural abnormalities is warranted.
Tests for secondary hypertension should be sent, including serum aldosterone and renin levels to assess for primary aldosteronism and plasma or 24-hour urine normetanephrine and metanephrine levels to assess for pheochromocytoma. Biochemical evaluation is the mainstay for endocrine hypertension evaluation and should be followed by imaging if abnormal results are found.
Intact parathyroid hormone (PTH) was 78 pg/mL (normal, 10-65 pg/mL), thyroid stimulating hormone 3.6 mIU/L (normal, 0.30-5.50 mIU/L), and morning cortisol 4.1 ug/dL (normal, >7.0 ug/dL). Plasma aldosterone was 14.6 ng/dL (normal, 1-16 ng/dL), plasma renin activity 3.6 ng/mL/hr (normal, 0.5-3.5 ng/mL/hr), and aldosterone-renin ratio 4.1 (normal, <20). Transthoracic echocardiogram showed LVH with normal valves, wall motion, and proximal aorta; the left ventricular ejection fraction was 70%. Magnetic resonance angiography of the renal vessels demonstrated no abnormalities.
