·
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.
·
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.
·
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.
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