Which is a classical clinical feature present in diabetes insipidus?

NORCET 5 Prelims - Sept 2023 (Shift-2)

Medical & Surgical Nursing

Easy

Appeared in: NORCET 5 Prelims - Sept 2023 (Shift-2)

Explanation

Polyuria, the excretion of abnormally large volumes of dilute urine, is the hallmark and primary clinical feature of Diabetes Insipidus (DI).
This occurs because of a deficiency in antidiuretic hormone (ADH) or the kidneys' inability to respond to ADH, preventing them from reabsorbing water.
Urine output can be massive, often exceeding 250 mL per hour, with a very low specific gravity (1.001 to 1.005), indicating it is mostly water.

Option B: Polydipsia (excessive thirst) is a classic symptom of DI, but it is a secondary, compensatory response to the massive fluid loss from polyuria. The primary problem is the water loss itself.
Option C: Homan's sign (pain in the calf on dorsiflexion of the foot) is a clinical assessment for Deep Vein Thrombosis (DVT). It has no association with Diabetes Insipidus.
Option D: Polyphagia (excessive hunger) is a classic symptom of Diabetes Mellitus (DM), not Diabetes Insipidus. In DM, cells are starved of glucose, leading to a constant feeling of hunger.

Visual 1: Flowchart: Pathophysiology of Diabetes Insipidus. This visual would illustrate how decreased ADH leads to decreased water reabsorption in the kidneys, causing polyuria, which in turn leads to dehydration and compensatory polydipsia.

Clinical Relevance

Nursing practice connection: Knowing Clinical Manifestations of Diabetes Insipidus helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must meticulously monitor fluid intake and output, daily weights, and urine specific gravity for patients with DI to assess fluid balance and the effectiveness of treatment (e.g., desmopressin).
It is critical for nurses to differentiate between DI and DM. While both can cause polyuria and polydipsia, the presence of polyphagia and hyperglycemia points towards DM, requiring entirely different management.
What if? If a patient with DI is unconscious or NPO (nothing by mouth), they cannot engage in compensatory polydipsia. This places them at extremely high risk for severe dehydration, hypernatremia, and cardiovascular collapse, constituting a medical emergency.

How to Approach the Question

First, identify the core condition in the question: 'Diabetes Insipidus'.
Recall the cardinal signs and symptoms of this endocrine disorder. The name 'insipidus' refers to the 'tasteless' or dilute nature of the urine, which is a strong clue.
Evaluate each option. 'Polyuria' (excessive urination) and 'Polydipsia' (excessive thirst) are the two main symptoms of DI.
Differentiate between the primary problem and the compensatory response. The inability to retain water (polyuria) is the core pathophysiological issue, while thirst (polydipsia) is the body's reaction to it. Therefore, polyuria is the most fundamental feature.
Eliminate the clearly incorrect options. 'Polyphagia' is a hallmark of Diabetes Mellitus, and 'Homan's sign' is used to assess for DVT, making them irrelevant to DI.

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