Labs: Pituitary and Gonadal Disorders Flashcards
A 45-year-old man seeks evaluation for weakness, fatigue, decrease of libido and loss of
body weight. Laboratory tests reveal low plasma levels of ACTH and TSH. What is the most likely diagnosis and which laboratory tests would be the most appropriate for the patient?
Simmond’s Syndrome - General Hypofunction of Pituitary.
Do complex stimulatory test: give GnRH (for LH/FSH), TRH (for prolactin), and insulin to stimulate the others (decreases Se Glucose, indirectly causing increase in GH).
Can also test for pituitary adenoma via MRI.
In a 29-year-old woman complaining of amenorrhea, plasma PL is elevated in association with low FSH and LH levels. Estrogen excretion is decreased. GnRH stimulation test was performed on three consecutive days. The first two tests were negative but after the third test a normal response was detected in plasma FSH and LH.
How do you interpret the result of the test and what is the most likely diagnosis?
Prolactinoma
Overproduction of prolactin causes inhibition of GnRH, which leads to low FSH and LH levels. Gonadatrophic cells atrophy, and due to atrophy, need to give GnRH repeatedly to have response.
Can do MRI for additional diagnosis. Therapy: bromocriptin which binds to dopamine receptors and inhibits prolactin secretion.
A 44-year-old man complains of impotence and galactorrhea. He has gynecomastia. Plasma PL is very high, FSH and LH are lower than normal. Plasma testosterone and urinary 17-ketosteroid excretion are decreased. After TRH or chlorpromazine stimulation there is only a minimal increase in plasma PL. What is the most likely diagnosis and what other tests would you perform?
Prolactinoma: galactorrhea and gynecomastia in male, PL elevation. Impotence due to ↑ PRL → ↓ GnRH → ↓ FSH/LH
Do stimulatory test or inhibitory test, bromocriptin treatment…
A 51-year-old man seeks evaluation for blurring of vision and headache. He has coarse facial features and enlarged extremities. The determination of which hormone would be the most straightforward in the patient? What other diagnostic procedure(s) would you order?
Acromegaly: Check Insulin-like GF-1 (IGF-1) because GH secretion is pulsatile and harder to measure accurately.
Image brain: sella turcica via MRI
Can perform GH suppression test: administer glucose and normally should see drop in GH, but with GH-secreting adenoma may have less drop, no drop, or paradoxical increase in GH.
In a 35-year-old woman, after the third delivery, lactation fails to start. She complains of loss of body weight and amenorrhea. Low voltage is found in her EKG tracing. Plasma levels of anterior pituitary hormones are very low. FT4 and FT3 are low. After TRH stimulation test neither TSH nor PL increase. Serum cholesterol level: 8.6 mmol/l. Is the problem primary, secondary or tertiary?
Sheehan Syndrome: post-partum hemorrhagic necrosis of pituitary due to final trimester ↑ PRL → pituitary swelling → pituitary more vulnerable to ↑ ICP during delivery → pituitary damage
This is a “secondary” problem bc with endocropathologies “primary” means problem in target organ like thyroid, and “tertiary” is a problem with hypothalamus
Se Cholesterol is high (>5.2) bc of hypothyroidism, low metabolism
A 37-year-old man complains of intense thirst (anadipsia) which commenced 7 days before. He drinks 5–6 l water a day, preferentially chilled water. His urine output is 6 l/24 h, the density is 1.004 kg/l. He is subjected to a water deprivation test with a duration of 8 h. During the test period he voids 4 l urine and the density does not exceed 1.005 kg/l in any of the collected fractions. What is the most likely diagnosis and which test would be the most effective in the differential diagnosis?
Diabetes Insipidus: not “primary polydipsia” (psychological hyper-thirst) bc urine is still not concentrated after water deprivation test (urine spec gravity in normal function is 1.25-1.35)
Must check if it’s central vs renal form via desmopressin test: administer ADH and check if urine volume ↓ / density ↑. Central DI: lack of ADH production, so should begin concentrating urine. Renal form: kidney does not respond to ADH by genetic or acquired causes, so giving ADH won’t make a large difference.
A 50-year-old woman complains of polyuria. She drinks 6–8 l water a day. Serum Na+: 138 mmol/l, urine output: 8 l/24 h, density: 1.004 kg/l. After salt loading urine volume decreases and the density increases. What is the most likely diagnosis?
Primary (psychological) Polydipsia: her urine density increases after salt-loading indicates she is capable of making concentrated urine, whereas people with diabetes insipidus cannot.
May be OCD, schizophrenic, etc.
The laboratory parameters of a 42-year-old man are: plasma prolactin and cortisol decreased, urinary 17-ketosteroid excretion is decreased, plasma prolactin level is not influenced by TRH. The administration of hCG increased the urinary excretion of 17-ketosteroids.
What is the possible diagnosis?
Panhypopituitarism (Simmond’s Syndrome)
↓ PRL indicates pituitary (secondary) low hormone production. ↓ cortisol and sex steroids indicates target glands (primary) low production. Because target glands responded to replacement of hCG, the problem is not with target glands. Because PRL level was unaffected by TRH administration, the hypothalamus (tertiary) is not the problem. So the problem is in the pituitary (secondary) hypofunction.
The laboratory parameters of a 19-year-old man are: plasma testosterone decreased, FSH and LH are elevated, urinary 17-ketosteroid excretion is decreased. The administration of hCG did not increase plasma testosterone level or the urinary excretion of 17-ketosteroids.
What is the possible diagnosis?
Primary Hypogonadism - hCG did not increase the hormone production from the target glands (gonads), and FSH/LH increase shows lack of neg feedback
May be due to Klinefelter’s sy, or maybe viral infection of gonads
The laboratory parameters of a 42-year-old man are: plasma testosterone increased significantly, FSH and LH are barely detectable, urinary excretion of androgens is increased. The right testis is enlarged. What is the possible diagnosis?
Primary Hypergonadism: ↑ T despite low gonadropins (being lowered via neg feedback) indicates primary hyperfunction.
May have androgen-secreting tumor in testis (right testis is enlarged)
