Neonatology: late neonatal hypocalcaemia: practice question

A Pediatrics question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pediatrics · Neonatology: late neonatal hypocalcaemia

Sample item

A 6-day-old term baby fed undiluted cow's milk is jittery and has a generalised seizure. Serum calcium is low, phosphate is high and glucose is normal. What is the most likely mechanism?

AVitamin K deficiency with bleedingBPerinatal asphyxia with renal tubular injuryCHigh phosphate load with a sluggish parathyroid responseDMaternal diabetes with fetal hyperinsulinism

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. High phosphate load with a sluggish parathyroid response

Late neonatal hypocalcaemia appears at 5 to 10 days in term babies fed cow's milk or high-phosphate formula. The phosphate load and immature parathyroid function lower calcium. Early hypocalcaemia in the first 72 hours is seen in preterm babies, infants of diabetic mothers and asphyxiated babies.

Option by option

A. Vitamin K deficiency with bleeding
Vitamin K deficiency causes bleeding and does not lower serum calcium.
B. Perinatal asphyxia with renal tubular injury
Asphyxia causes early hypocalcaemia, and this baby is well apart from the feeding history.
C. High phosphate load with a sluggish parathyroid response (correct)
Correct. The phosphate load of cow's milk with transient parathyroid immaturity causes late hypocalcaemia.
D. Maternal diabetes with fetal hyperinsulinism
Infants of diabetic mothers develop hypocalcaemia early, within the first 72 hours.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Pediatrics question

What is the answer to this Pediatrics question?

The best answer is C, High phosphate load with a sluggish parathyroid response. Late neonatal hypocalcaemia appears at 5 to 10 days in term babies fed cow's milk or high-phosphate formula.

Why is "Vitamin K deficiency with bleeding" not the answer?

Vitamin K deficiency causes bleeding and does not lower serum calcium.

Why is "Perinatal asphyxia with renal tubular injury" not the answer?

Asphyxia causes early hypocalcaemia, and this baby is well apart from the feeding history.

Why is "Maternal diabetes with fetal hyperinsulinism" not the answer?

Infants of diabetic mothers develop hypocalcaemia early, within the first 72 hours.

What concept does this question test?

It tests Neonatology: late neonatal hypocalcaemia in Pediatrics. The phosphate load and immature parathyroid function lower calcium. Early hypocalcaemia in the first 72 hours is seen in preterm babies, infants of diabetic mothers and asphyxiated babies.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Neonatology: late neonatal hypocalcaemia?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.