Which lab tests are performed to confirm the diagnosis of diabetes insipidus (DI)?

Updated: Mar 18, 2020
  • Author: Romesh Khardori, MD, PhD, FACP; Chief Editor: George T Griffing, MD  more...
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In a patient whose clinical presentation suggests diabetes insipidus (DI), laboratory tests must be performed to confirm the diagnosis. A 24-hour urine collection for determination of urine volume is required. In addition, the clinician should measure the following:

  • Serum electrolytes and glucose

  • Urinary specific gravity

  • Simultaneous plasma and urinary osmolality

  • Plasma antidiuretic hormone (ADH) level

Perform testing with the patient maximally dehydrated as tolerated—that is, at a time when ADH release is the highest and his/her urine is the most concentrated. Water deprivation testing may be useful in situations in which the diagnosis is uncertain.

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