MLT GlobeChemistry: Endocrinology – page 2
123 Chemistry MCQs on Endocrinology with answers and explanations.
A patient has multiple refractory peptic ulcers and diarrhoea. Which fasting serum hormone would be greatly raised?
A gastrinoma (Zollinger–Ellison syndrome) greatly raises gastrin and acid output. A paradoxical rise in gastrin after secretin confirms it.
Which finding would NOT be expected in overt hypothyroidism?
A low metabolic rate causes cold intolerance, weight gain, constipation and bradycardia. Heat intolerance with weight loss suggests hyperthyroidism.
Thyroid tests show high TSH with low free T4 and low free T3. What is the most likely category?
Failure of the thyroid gland (often Hashimoto thyroiditis) lowers FT4/FT3, and feedback raises TSH. Central hypothyroidism gives low or normal TSH.
Which estrogen is the main ovarian product in premenopausal women and the one measured to assess follicular function?
Estradiol from growing follicles is monitored during ovarian stimulation. Estriol comes mainly from the fetoplacental unit, and estrone predominates after menopause.
In most patients with acromegaly, where does the excess growth hormone come from?
More than 95% of acromegaly is caused by a GH-secreting pituitary adenoma. Ectopic GHRH or GH production is rare.
A tall man with small firm testes has a 47,XXY karyotype. Which hormone profile is expected?
Klinefelter syndrome causes primary testicular failure. Loss of negative feedback from testosterone and inhibin B raises LH and FSH.
A patient has central obesity, purple striae, a moon face and hypertension. Excess of which hormone explains this?
These are features of Cushing syndrome, caused by long-term glucocorticoid excess. Aldosterone excess causes hypertension and hypokalaemia without these body changes.
A patient with thyrotoxicosis and a diffuse goitre is being investigated. Which antibody is specific for Graves disease?
TRAb stimulates the TSH receptor and causes Graves hyperthyroidism. TPO and thyroglobulin antibodies are also common in Hashimoto thyroiditis.
A woman has hirsutism that has progressed quickly. Which hormones are measured first to look for an ovarian or adrenal androgen source?
Very high testosterone suggests an ovarian source and high DHEA-S an adrenal source. Rapid virilisation raises concern for a tumour.
In the testis, which hormone acts on Sertoli cells to make androgen-binding protein?
FSH stimulates Sertoli cells to make androgen-binding protein and inhibin B, which support spermatogenesis. LH acts on Leydig cells to make testosterone.
Which hormone pattern is typical after menopause?
Without ovarian follicles, estradiol and inhibin fall, so FSH (more than LH) rises through loss of negative feedback.
Which glucocorticoid is the main one secreted by the human adrenal cortex?
The zona fasciculata secretes about 10–20 mg of cortisol a day. Corticosterone is the main glucocorticoid in rodents, and aldosterone is a mineralocorticoid.
Which finding is typical of Cushing syndrome?
Cortisol drives gluconeogenesis and causes insulin resistance, so hyperglycaemia is common. Addison disease, not Cushing, causes hyperkalaemia and hyponatraemia.
A hypertensive patient has hypokalaemia, suppressed renin and an adrenal adenoma. What is the diagnosis?
Autonomous aldosterone secretion causes sodium retention, potassium loss and renin suppression. Adenomas and bilateral hyperplasia are the common causes.
Overall, what is the most common cause of Cushing syndrome?
Iatrogenic steroid use is the most common cause. Among endogenous causes, pituitary Cushing disease is the most frequent.
What distinguishes Cushing 'disease' from other forms of Cushing syndrome?
'Cushing disease' is used only for pituitary ACTH-driven hypercortisolism. All other causes come under Cushing syndrome.
Which is a first-line screening test for suspected Cushing syndrome?
The overnight 1 mg DST, late-night salivary cortisol and 24-hour UFC are the screening tests. CRH testing and IPSS are used later to localise the cause.
A patient with flushing, diarrhoea and a liver mass is suspected to have a midgut carcinoid tumour. Which urine test is used?
Carcinoid tumours make serotonin, which is metabolised to 5-HIAA. Bananas, walnuts and some drugs can falsely raise results.
Besides its excretory role, the kidney makes which hormone that stimulates red cell production?
Peritubular interstitial cells release EPO in response to hypoxia. The kidney also makes renin and calcitriol. Thrombopoietin, angiotensinogen and hepcidin come mainly from the liver.
Why should creatinine be measured on a 24-hour urine sent for VMA or metanephrines?
Creatinine excretion is fairly constant, so a low value suggests under-collection. Specimens are usually acidified with HCl, and interfering drugs should be reviewed.