Laboratory Diagnosis of the disorders of the Hypothalamus and the Pituitary Gland

Question 1

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?

Answer 1

Clinical Findings:
>weakness, fatigue, lost of BW ->symptoms of decr cortisol and GH
>Loss of libido -> decreased Gonadotropins

Lab findings:
there is decrease in ACTH and TSH

Conclusion:

• indicates Panhypopituarism (whole pit has hypofunction)
• Likely due to Hormone Negative Macroadenoma of Pit.Gland (that compresses the trophic cells)
• other reasons: BS/ Tumour growing nearby/ mech damage due to trauma/ storage diseases with toxic deposition.
• with progression hypofunction of all target organs of the Ant.Pit.
• *order of Loss: GH->LH->FSH->ACTH->TSH

Further Tests:

1) Stimulation Test (to check if problem secondary)
2) Insulin tolerance Test
(give insulin to see if ACTH and Cortisol and GH goes up)
3)X-ray/MRI/CT
4)Check decrease in post pit hormones (ADH/Oxytoxicin)
(by waterdeprivation test)

Question 2

In a 29-year-old woman complaining of amenorrhea, plasma PL is found 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?

Answer 2

Clinical Findings:
-Amonorrhea

Lab findings:

• elevated PL
• Decreased FSH and LH and Estrogen

Conclusion:
-most likely a PL SECRETING ADENOMA (because PL inhibits FSH/LH secretion by inhibiting GnRH production)

• with adminstration of GnRH first no change as it takes some time for Gonadtropes to secrete hormones (rules out Panhypopituitarism as cells are working)
• patient could have hypothalamus damage (rare)

Tests:
-Imaging to found adenoma

Treatment:
-Bromocription (can pass thru BBB and no circulatory side effects)

Question 3

A 44-year-old man complains of impotence and galactorrhea. He has gynecomasty.
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?

Answer 3

Clinical:
-impotence, galactorrhea and tits -> Hyperprolactinema (perhaps a prolactin secreting adenoma)

Lab findings:

• serum PL up
• FSH/LH/Testerone/ 17-ketosteroid decreased due to decre GnRH

Conclusion:

• minimal increase in PL after TRH/chlorpromazine
• TRH -> TSH + prolactin releasing factor
• Chlorpromazine -> Stimulates prolactin secretion (indicates there is physiological response in normal prolactin secreting cells in pit)

Hyperprolactinemia -> Prolactin secreting adenoma

Tests:
imaging look for adenoma

Treatment:
Bromocriptine

Question 4

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?

Answer 4

Clinical Findings:

• Blurred vision -> compression of optic chiasm
• enlarged extremities/Coarse facial features in middle age -> ACROMEGALY (incr GH secretion)
• Headache: probably a growing Adenoma (exerting pressure cause bitemporal hemianopsia)

Features of Acromegaly:

• growing, hand and ears get bigger
• renal disease
• GH is insulin antagonist (DM)

Tests:

1) measuring serum GH (but it’s pulsatile) so measure IGF-1
2) GH supression test: give glucose -> hyperglycemia -> In healthy patients insulin will cause decrease in GH (no change in GH)
3) X-ray: check adenoma

Question 5

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?

Answer 5

Clinical findings:

• agalactorrhea is first sign of sheehan syndrome (postpartum hypopituitarism
• also loss of BW and Amenorrhea
• decrease in TH and low voltage ECG -> indicate Hypothyroidism

Lab findings:

• low anterior pituitary hormones in serum
• low levels of FT3/FT4 (due to decrease in TSH)
• hypercholestremia due to longterm hypothyroidism

Conclusion:

• after stimulation still low level of TSH and PL ->problem on secondary level
• Sheehan syndrome (loses lots of of blood, or has been hypotensive)

Question 6

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 in any of the collected fractions.
What is the most likely diagnosis and which test
would be the most effective in the differential diagnosis?

Answer 6

Clinical Findings:

• drinking lots of water indicates Diabetes Insipitus (Central, Nephrogenic)
• Large urine output

Lab findings:
-His urine fails to concentrate during water deprivation (instead plasma osmalirity concentrate)

Further Tests:

• Nasal Desmopressin (ADH anaogue) to see if central or nephrogenic
• if urine concentrates ->central
• if urine doesn’t -> Nephrogenic

Question 7

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?

Answer 7

Salt loading:
-ptnt given IV with increased salt conc -> inc Blood [Na] -> increase ADH -> should see decrease in urine volume and increase in density of urine (IN DI NO CHANGE)

Lab findings:
-urine volume down
-urine density goes up
INDICATES NO DI

Conclusion:

• ptnt has pyscogenic polydipsia
• it’s an obsessive compulsive disorder -> where ptnt drinks alot to clean themselves inside