Diagnosis of Diabetes Insipidus (DI)

Diabetes insipidus is a disease in which large volumes of dilute urine (polyuria) are excreted due to vasopressin (AVP) deficiency [central diabetes insipidus (CDI)], AVP resistance [nephrogenic diabetes insipidus (NDI)], or excessive water intake (primary polydipsia). Polyuria is characterized by a urine volume in excess of 2 l/m2/24 h or approximately 150 ml/kg/24 h at birth, 100–110 ml/kg/24 h until the age of 2 years and 40–50 ml/kg/24 h in the older child and adult.

Diabetes insipidus (DI) is defined as the passage of large volumes (>3 L/24 hr) of dilute urine (< 300 mOsm/kg). It has the following 2 major forms:

  1. Central (neurogenic, pituitary, or neurohypophyseal) DI, characterized by decreased secretion of antidiuretic hormone (ADH; also referred to as arginine vasopressin [AVP])
  2. Nephrogenic DI, characterized by decreased ability to concentrate urine because of resistance to ADH action in the kidney

Two other forms are gestational DI and primary polydipsia (dipsogenic DI); both are caused by deficiencies in AVP, but the deficiencies do not result from a defect in the neurohypophysis or kidneys.




Diagnosis of Diabetes Insipidus (DI)
If the clinical presentation suggests DI, laboratory tests must be performed to confirm the diagnosis, as follows:

  1. A 24-hour urine collection for determination of urine volume
  2. Serum electrolyte concentrations and glucose level
  3. Urinary specific gravity
  4. Simultaneous plasma and urinary osmolality
  5. Plasma ADH level

Additional studies that may be indicated include the following:

  1. Water deprivation (Miller-Moses) test to ensure adequate dehydration and maximal stimulation of ADH for diagnosis
  2. Pituitary studies, including magnetic resonance imaging (MRI) and measurement of circulating pituitary hormones other than ADH

 

 

References:

  1. Robertson GL. Diabetes insipidus: Differential diagnosis and management. Best Pract Res Clin Endocrinol Metab. 2016 Mar;30(2):205-18 [Medline]
  2. Kalra S, Zargar AH, Jain SM, Sethi B, Chowdhury S, Singh AK, Thomas N, Unnikrishnan AG, Thakkar PB, Malve H. Diabetes insipidus: The other diabetes. Indian J Endocrinol Metab. 2016 Jan-Feb;20(1):9-21. [Medline]
  3. Di Iorgi N, Napoli F, Allegri AE, Olivieri I, Bertelli E, Gallizia A, Rossi A, Maghnie M. Diabetes insipidus- diagnosis and management. Horm Res Paediatr. 2012;77(2):69-84. [Medline]

 

Created Sep 13, 2018.

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