Endocrine Disorders - Diagnostic Tests

Question 1

Hypopituitarism

Answer 1

–cranial CT scan or cranial MRI, revealing a tumor or abnormal mass in the pituitary gland
–Blood levels of serum luteinizing hormone (LH), serum follicle stimulating hormone (FSH), or serum thyroid stimulating hormone (TSH), decreased or normal
serum testosterone serum estradiol (estrogen), serum cortisol, serum ACTH, levels, decreased
–T4 (thyroid hormone), decreased
–serum growth hormone (GH), decreased

Question 2

Diabetes Inspidius

Answer 2

• -General lab work
• -24 hour I & O: Urine output must exceed 4 L to diagnosis diabetes insipidus. 24 hr. urine output will usually be between 4 and 30 L/day.
• -“water deprivation” or dehydration test: measure urine output, specific gravity, osmolarity and weight hourly.
• -CT or MRI scans

Question 3

Addision’s (adrenal hypOfunction)

Answer 3

• -Lab tests reveal: low serum cortisol (22pmol/L) low blood glucose, hyponatremia, hyperkalemia, increased BUN,
• -Secondary disease also has low serum ACTH, ACTH stimulation test does not cause the usual increase in cortisol levels
• -CT, MRI, skull X-ray, or angiography to detect tumors or atrophy.
• -Urinary testing for glucocorticoid metabolite: 17-hydroxycortico- steroid

Question 4

Cushing’s (adrenal hypERfunction)

Answer 4

–Overnight Dexamethasone suppression tests for Cushing’s disease. In normal subjects giving dexamethasone will suppress cortisol secretion.
–Urine for free cortisol and metabolites- Done as a 24 hr. collection. Urine Ca+, K+, and glucose will be elevated.
–Elevated plasma cortisol levels- try and get the sample at the same time each day as levels normally fluctuate
ACTH levels may be elevated
–Increased glucose, and sodium
–Decreased serum calcium and potassium and lymphocyte count

Radiological exams:

• X-rays of skull, chest and abdomen.
• Angiography
• Nuclear cans
• CT scans
• MRI
• Ultrasonography

Question 5

Hyperthyroidism

Answer 5

Lab tests:

• Triiodothyronine (T₃)
• Thyroxine (T₄)
• T₃ resin uptake (T₃RU)
• Thyroid-stimulating hormone (TSH)
• TSH antibodies (TSH-Rab) for Graves disease

Diagnostic Tests:

• Thyroid scan: radioactive iodine is given by mouth or IV (RAI[¹²³]) and the uptake by the thyroid is monitored.
• Ultrasound
• EKG
• CT or MRI
• -**Fine needle aspiration biopsy!! (25 to 27 gauge needle)

Question 6

Thyroid Cancer

Answer 6

• Blood test
• Thyroid scan
• CT or MRI

Question 7

HypERparathyroidism

Answer 7

• Lab results: High levels of PTH along with persistent hypercalcemia and low phosphate
• Bone density studies
• CT or Nuclear Medicine Scans

Question 8

HypOparathyroidism

Answer 8

Diagnostic tests:

• EEG
• CT
• Blood levels of calcium, Mg, phosphate and Vitamin D.

Question 9

Hyperaldosteronism

Answer 9

• Low serum potassium level
• Abdominal CT scan that shows adrenal mass
• Elevated plasma and urine aldosterone levels
• Low plasma renin activity
• ECG that shows abnormalities associated with low potassium levels