Biochemistry — Calcium, Bone Chemistry and Thyroid Tests, NMC MBBS licence examination syllabus (Nepal Medical Council).
NMC-style practice questions written for this site. They are not past questions, and no past paper has been reproduced.
An inpatient with sepsis has a low total calcium. The albumin is also low. Why might no treatment be required?
Answer: Because much of the circulating calcium is bound to albumin and physiologically inactive. A low albumin lowers the total without lowering the free, active fraction, so the patient may have normal active calcium. The adjusted value, not the total, is what should guide action.
A well 55-year-old is found to have a high calcium on a routine test, with a parathyroid hormone in the middle of the reference range. How should this be interpreted?
Answer: As inappropriate. When calcium is high the parathyroid hormone should be suppressed; a level that is merely "normal" is therefore abnormal in context and points to primary hyperparathyroidism. The question is never whether a hormone is in range but whether it is appropriate for what the body is asking.
A patient with known lung cancer has a high calcium, weight loss and confusion. What would you expect the parathyroid hormone to show?
Answer: Suppressed, which is the appropriate response to a high calcium. Its suppression supports malignancy-associated hypercalcaemia rather than excluding a diagnosis — it shows the parathyroid glands are behaving normally and the calcium is being driven by something else.
A thyroid panel shows a low gland hormone with a low pituitary hormone. Why is this not simple hypothyroidism?
Answer: Because in primary gland failure the pituitary hormone rises as the pituitary pushes harder. Both being low means the gland is not being driven, which places the problem above it — in the pituitary or hypothalamus.
An acutely unwell inpatient has a mildly abnormal thyroid panel. Why should treatment usually wait?
Answer: Because serious illness disturbs thyroid results in ways that mimic disease, and the abnormality often resolves with recovery. Unless the clinical picture is compelling, repeating the tests once the patient has recovered avoids treating an illness-related artefact as thyroid disease.
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