Question

which one of the following clinical features differentiates diabetes mellitus from diabetes insipidus? polyuria dehydration polydipsia polyphagia

Explanation:

• Polyuria: Both Diabetes mellitus (due to hyperglycemia, osmotic diuresis) and Diabetes insipidus (due to ADH deficiency, inability to concentrate urine) cause polyuria. So this is not a differentiating feature.
• Dehydration: Both conditions, due to excessive urination, can lead to dehydration. So this is not a differentiating feature.
• Polydipsia: Both conditions, as a result of polyuria (leading to fluid loss), cause polydipsia (increased thirst) as the body tries to compensate for fluid loss. So this is not a differentiating feature.
• Polyphagia: Polyphagia (increased hunger) occurs in Diabetes mellitus because cells are unable to take up glucose (due to insulin deficiency or resistance), so the body signals for more food to get energy. Diabetes insipidus is related to water balance (ADH issue) and does not involve problems with glucose utilization, so polyphagia is not a feature of Diabetes insipidus. Thus, polyphagia differentiates Diabetes mellitus from Diabetes insipidus.

Answer:

The correct option is: Polyphagia (the last option in the list, with the label as per the options: the option with "Polyphagia"). In the given options, it is the fourth option (assuming the order is Polyuria, Dehydration, Polydipsia, Polyphagia). So in boxed form (but as per the instruction, just the option text with identifier if needed, but here the options are listed as:

1. Polyuria
2. Dehydration
3. Polydipsia
4. Polyphagia

So the answer is 4. Polyphagia (or just stating the option text: Polyphagia)