Fast Five Quiz: Test Your Knowledge of Diabetes Insipidus

Romesh Khardori, MD, PhD

Disclosures

May 30, 2018

The physical examination findings vary with the severity and chronicity of diabetes insipidus. The examination findings may be entirely normal. Hydronephrosis, with pelvic fullness, flank pain or tenderness, or pain radiating to the testicle or genital area, may be present. Bladder enlargement occurs in some patients. Unless the thirst mechanism is impaired or access to fluid is restricted, dehydration is not seen. Aside from an enlarged bladder, no specific signs of diabetes insipidus exist.

The most common form of diabetes insipidus is central diabetes insipidus after trauma or surgery to the region of the pituitary and hypothalamus. It may exhibit one of three patterns: transient, permanent, or triphasic. The triphasic pattern is observed more often clinically. Whether improvements in surgical techniques and approaches have altered the frequency of the triphasic pattern has not been well studied.

The first phase of the triphasic pattern is a polyuric one that lasts 4-5 days, caused by inhibition of ADH. An immediate increase in urine volume and a concomitant fall in urine osmolality occur. The second phase is an antidiuretic one that lasts 5-6 days, resulting from the release of stored hormone; urine osmolality rises. The third phase can be permanent diabetes insipidus, when stores of ADH are exhausted and the cells that produce ADH are absent or unable to produce more.

In infants with diabetes insipidus, the most apparent signs may be the following:

  • Crying

  • Irritability

  • Growth retardation

  • Hyperthermia

  • Weight loss

Pregnancy is associated with an increased risk for diabetes insipidus, but this form remits after delivery. In addition, pregnancy may unmask subclinical or mild central diabetes insipidus.

For more on the presentation and physical examination of patients with diabetes insipidus, read here.

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