Internal-Medicine

Answers and Explanations
1. (C) Primary hypothyroidism is the most
common cause of hypothyroidism in adults.
Primary hypothyroidism is several times more
common in women than in men and occurs most
often between the ages of 40 and 60. Postablative
hypothyroidism (radiation or surgery induced)
is also very common. (Felig, p. 316)
2. (B) Diminished concentrating ability and proteinuria
occur even when the glomerular filtration
rate is near normal. The severity of renal
involvement correlates with the duration and
magnitude of serum uric acid elevation. Uric
acid and monosodium urate deposit in the
renal parenchyma. These deposits can cause
intrarenal obstruction and elicit an inflammatory
response as well. Hypertension, nephrolithiasis,
and pyelonephritis can also contribute to
the nephropathy of gout. (Kasper, p. 1704)
3. (E) With pituitary hypofunctioning, gonadotropin
deficiency is the most common early manifestation
in both men and women. Growth hormone
secretion is also impaired early on, but is
less clinically apparent. (Felig, p. 681)
4. (C) Disease states, due to abnormal intracellular
receptors, include androgen insensitivity;
cortisol resistance; vitamin D-dependent rickets,
type II; thyroid hormone resistance; and
pseudohypoaldosteronism. Androgen insensitivity
syndrome is caused by a mutation in the
androgen receptor, and it affects 1 in 100,000
chromosomal males. Because the androgen
receptor is X-linked, it only affects males. The
phenotypic presentation can vary from complete
androgen insensitivity (female external
features) to partial insensitivity causing
ambiguous or normal male features and infertility.
There are several different types of cell
membrane receptors. (Kasper, pp. 2217–2218)
5. (D) Beta-carotene increases the patient’s tolerance
for sunlight, apparently by quenching
active intermediates. Beta-carotene is an effective
scavenger of free radicals. Although many
affected individuals can tolerate sun exposure
while taking beta-carotene, it has no effect on
the basic metabolic defect in porphyrin-heme
synthesis. (Kasper, p. 2308)
6. (E) FSH is said to encourage maturation of a
follicle in the human menstrual cycle. The cardinal
hormonal change in phase I is a rise in
FSH caused by a decrease in the level of estrogens
and a waning activity of the corpus
luteum. In men, FSH stimulates Sertoli cells,
which have an important role in spermatogenesis.
(Kasper, p. 2094)
7. (E) In hyperparathyroidism, bony lesions are
lytic and can cause pain. The cortical surfaces
are thinned and much of the bone is demineralized.
The fibrotic bulging lesions within bone
are termed brown tumors. Fluid-filled cysts can
also occur (osteitis fibrosa cystica). Anemia is
common, and the QT interval can be shortened
if the calcium is high enough. Hypertension is
common. Most patients with hyperparathyroidism
have a simple adenoma that functions
autonomously, so that hormone is secreted
with high calcium. In about 10–15% of cases,
hyperplasia of all the parathyroid glands (chief
cell hyperplasia) is the cause. Differentiation
from adenoma is important to determine the
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