Diabetes insipidus is caused by?

NHM UP Staff Nurse - 2019

Medical Surgical Nursing

Easy

Appeared in: NHM UP Staff Nurse - 2019

Explanation

Diabetes Insipidus (DI) is a disorder of water balance caused by a deficiency of antidiuretic hormone (ADH), also known as vasopressin.
ADH is released from the posterior pituitary and acts on the kidneys to increase water reabsorption.
A lack of ADH (central DI) or the kidneys' failure to respond to it (nephrogenic DI) prevents water reabsorption.
This results in the classic symptoms of DI: polyuria (excretion of large volumes of dilute urine) and polydipsia (intense thirst).

Option A: A decreased production of thyroid hormone causes hypothyroidism, which is characterized by a slowed metabolism, weight gain, and cold intolerance, not the polyuria seen in Diabetes Insipidus.
Option B: Decreased secretion of insulin causes Diabetes Mellitus, a disorder of glucose metabolism. While Diabetes Mellitus can also cause polyuria, it is due to osmotic diuresis from high blood sugar (hyperglycemia), not a primary water balance issue.
Option C: Decreased secretion of parathyroid hormone (PTH) causes hypoparathyroidism. This condition leads to low blood calcium levels (hypocalcemia), resulting in symptoms like muscle spasms, tingling, and tetany.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of Diabetes Insipidus as background academic context rather than a clinical decision trigger.
A key nursing responsibility is to differentiate between Diabetes Insipidus and Diabetes Mellitus, as both can present with 'polys' (polyuria, polydipsia) but have different pathophysiology and management.
For patients with DI, nurses must prioritize fluid replacement and monitor for signs of severe dehydration, such as hypotension, tachycardia, and altered mental status.
What if? If a patient post-head surgery suddenly starts producing over 200 mL of urine per hour for two consecutive hours with a low specific gravity, the nurse should suspect the onset of central DI and immediately notify the healthcare provider, as prompt treatment with desmopressin may be required.

How to Approach the Question

First, identify the key term in the question: 'Diabetes Insipidus'.
Recognize this is a factual recall question about endocrine system pathophysiology.
Differentiate 'Diabetes Insipidus' (a water balance problem related to ADH) from 'Diabetes Mellitus' (a glucose metabolism problem related to insulin). This immediately helps evaluate the options.
Analyze the function of each hormone in the options. ADH controls water reabsorption in the kidneys.
Conclude that a deficiency in the hormone responsible for water retention (ADH) would lead to excessive water loss, which is the hallmark of Diabetes Insipidus.

Concept Tested & Keywords

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E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 1072-1074

E6 Physiology Essentials Sembulingam 10e Part 2 p. 34-36

E6 Medicine Harrison 22e Part 2 p. 920-922