Endocrinology

·         The most definitive and widely accepted test for the DIAGNOSIS OF ACROMEGALY is the response of growth hormone during an oral glucose tolerance test. Typically, the growth hormone at baseline in acromegaly will be greater than 5 g/L. In normal patients, the growth hormone will suppress to less than 2 with an oral glucose tolerance test (OGTT). In patients with acromegaly the GH values may rise, show no change, or suppress partially but not less than 2.

·         Because abnormalities in fasting and postprandial glycemia tend to progress in tandem, FBG measurement has supplanted the oral glucose tolerance test for the diagnosis of diabetes except during pregnancy.

·         With aging, there is a relatively small decrease in serum total testosterone level; free testosterone decreases to a greater degree; SHBG increases.

·         A random plasma ACTH level greater than 10 µg/ml is indicative of ACTH-dependent Cushing syndrome.

The critical test for the diagnosis of chronic adrenal insufficiency is the cosyntropin test.

·         The incidence of pheochromocytoma is markedly increased in several genetic syndromes: multiple endocrine neoplasia type 2a and type 2b; and the phakomatoses, including neurofibromatosis, cerebelloretinal hemangioblastosis, tuberous sclerosis, and Sturge-Weber syndrome. The treatment of pheochromocytoma is surgical. Before the surgical procedure, complete alpha blockade should be induced to avoid intraoperative hypertensive crisis. Preparation should begin 7 days before the planned procedure, using phenoxybenzamine at an initial dosage of 10 mg by mouth twice daily. The dose should be increased daily so that by the seventh day, the patient is taking at least 1 mg/kg/day in three divided doses.

·         Appropriate initial evaluation of a patient with hypercalcemia is to Measure the parathyroid hormone [PTH] level with a two-site immunoradiometric assay [IRMA, or so-called intact PTH] and assess 24-hour urinary calcium output.

·         National Institutes of Health Workshop on Asymptomatic Primary Hyperparathyroidism defined the following indications for surgical intervention: (1) significant bone, renal, gastrointestinal, or neuromuscular symptoms typical of primary hyperparathyroidism; (2) elevation of serum calcium by 1 mg/dl or more above the normal range; (3) marked elevation of 24-hour urine calcium excretion (> 400 mg); (4) decreased creatinine clearance (reduced by 30%); (5) significant reduction in bone density (T score < –2.5); (6) consistent follow-up is not possible or is undesirable because of coexisting medical conditions; and (7) age less than 50 years.

·         A normal serum glucose concentration, reliably obtained during the occurrence of spontaneous symptoms, eliminates the possibility of a hypoglycemic disorder; no further evaluation for hypoglycemia is required.

·         NIPHS is a recently described entity. Like insulinoma, it affects patients across a broad age range (16 to 78 years) and causes severe neurohypoglycemia, with loss of consciousness and, in some cases, generalized seizures. Unlike insulinoma, it occurs predominantly in males (70%). Histologic analysis of pancreatic tissue from patients with NIPHS shows cells budding off ducts, seen best by chromogranin A immunohistochemical staining. Islet cell hypertrophy is also evident. No gross or microscopic tumor has been identified in any patient with NIPHS. Symptoms of NIPHS occur primarily in a postprandial state, usually 2 to 4 hours after eating. Although patients with insulinoma may experience symptoms postprandially, they also have symptoms during food deprivation. It is extremely rare for insulinoma patients to have symptoms solely in the postprandial state. Results of supervised 72-hour fasts have always been negative in NIPHS patients. A negative 72-hour fast in a patient with insulinoma is a rare occurrence. Gradient-guided partial pancreatectomy has been effective in relieving symptoms in patients with NIPHS, though recurrence of hypoglycemia after a few symptom-free years has been reported in a few patients.

·         A National Institutes of Health expert panel has suggested that patients whose BMI is 30 kg/m2 or more or who have a BMI of 27 kg/m2 or more plus obesity-related risk factors (i.e., diabetes, hypertension, or hyperlipidemia) could be considered for pharmacologic therapy. Patients with a BMI of 40 kg/m2 or more or a BMI of 35 kg/m2 or more plus obesity-related risk factors could be considered for surgical therapy.

·         The National Cholesterol Education Program Adult Treatment Panel III has suggested five clinical variables as diagnostic criteria for the metabolic syndrome: (1) increased waist circumference, (2) increased triglyceride level, (3) decreased HDL cholesterol level, (4) increased blood pressure, and (5) elevated level of fasting plasma glucose. A diagnosis of the metabolic syndrome is made when three or more of these clinical variables are present. Aerobic exercise and a diet low in saturated fat are indicated as therapy for most people with the metabolic syndrome. More aggressive therapy is indicated if the metabolic syndrome is severe or if the patient has familial combined hyperlipidemia or type 2 diabetes mellitus.

·         Treatment of AIP attack is aimed at eliminating or avoiding any inciting factors; achieving appropriate volume resuscitation with attention to sodium disorders; maintaining adequate nutrition, particularly carbohydrates; and temporarily blocking porphyrin synthesis. Thus, intravenous administration of fluid with both sodium chloride and dextrose is appropriate, as is identification and treatment of infection. Hematin, an inhibitor of porphyrin synthesis, is also effective in stopping acute attacks.

·         PCT is probably the most common of the porphyrias. It manifests as vesicle formation in sun-exposed areas, particularly the dorsum of the hands, followed by scarring and hyperpigmentation. It is frequently associated with liver abnormalities. PCT results from an inherited or acquired deficiency in uroporphyrinogen decarboxylase; the acquired form is frequently associated with excessive alcohol ingestion and iron overload. Therefore, the serum ferritin level is typically elevated. Plasma porphyrin levels are also elevated, as are urinary porphyrin levels, leading to urinary fluorescence under ultraviolet light. A finding that is virtually diagnostic of PCT is the presence of isocoproporphyrin in stool.