Urinary Arginine Vasopressin (AVP) Measurement in Children: Water Deprivation Test Incorporating Urinary AVP
| Title: | Urinary Arginine Vasopressin (AVP) Measurement in Children: Water Deprivation Test Incorporating Urinary AVP |
|---|---|
| Author: | Shimura, Naoto |
| Publisher: | Acta Paediatrica Japonica |
| Date Published: | August 01, 1993 |
| Reference Number: | 124 |
The value of a water deprivation test incorporating urinary arginine vasopressin (AVP) measurement was investigated in 13 patients with polydipsia and/or polyuria (complete central diabetes insipidus [CCDI] in four; incomplete central diabetes insipidus [ICDI] in five; secondary nephrogenic diabetes insipidus [NDI] in three; compulsive water drinking [CWD] in one) and a group of 25 control subjects. Urine samples were collected after water deprivation during sleep and the urinary osmolalities and AVP concentrations were measured. Analysis of the results of 104 urine samples from the 25 control subjects demonstrated a close correlation between urinary osmolality and AVP (r = 0.89, P < 0.001). After water deprivation during sleep, the respective mean maximal urinary osmolalities and AVP concentrations were: 127.4 +/- 34.4 mOsm/kg and 1.1 +/- 0.5 pg/mL in the patients with CCDI (14 samples, four children); 410.3 +/- 101.8 and 6.1 +/- 3.5 in those with ICDI (16 samples, five children); 348.7 +/- 71.2 and 100 +/- 45.1 in those with NDI (nine samples, three children); 541.5 +/- 143.5 and 43.6 +/- 33.2 in the patient with CWD (two samples, one child) and 898.8 +/- 186.3 and 97.4 +/- 50.4 in group C (54 samples, 18 children). Furthermore, the urinary AVP level relative to the osmolality in each patient varied depending on the AVPO secretion status and renal concentrating ability. Each patient, except the one with CWD, could be discriminated from the normal subjects using this test. It seems that this test is easy to perform and useful for diagnosis and follow-up of patients with partial/complete posterior pituitary function defects and those with renal concentration impairment.
This translation by the NDI Foundation is to assist the lay reader. To provide a clear, accessible interpretation of the original article, we eliminated or simplified some technical detail and complicated scientific language. We concentrated our translation on those aspects of the article dealing directly with NDI. The NDI Foundation thanks the researchers for their work toward understanding and more effectively treating this disorder.
© Copyright NDI Foundation 2007 (JC)
Shimura conducted a study to determine the effectiveness of a less invasive diagnostic technique which involved depriving subjects of water overnight then measuring the amount of AVP found in the subjects' urine the following morning and correlating it with the osmolality (the concentration of particles in the urine per kilogram of urine). Shimura conducted the study on 13 patients with polydipsia and polyuria: four had complete CDI; five had incomplete CDI; three had NDI; and one was a compulsive water drinker. He compared the results with 25 healthy control subjects who were subjected to the same conditions and measurements.
The control subjects showed a close correlation between the amount of AVP in their urine and their urinary osmolality. They averaged a healthy amount of AVP and their urine osmolality was in the normal range. The patient with CWD had readings very close to the normal range. Patients with ICDI evidenced much lower urinary AVP and much lower urinary osmolality, and the patients with CCDI had lower averages yet. The AVP concentration in the NDI group was significantly higher than those in the CCDI and ICDI group, though much lower than the control group. But the urinary osmolality of the NDI group did not differ significantly from the CCDI and ICDI groups.
The test showed that after water deprivation the urinary osmolality and AVP concentrations in the control groups and the patient with CWD increased. The measures of the CCDI and ICDI groups did not. And though the NDI urinary AVP readings increased after water deprivation (to almost the level of the control group) their urinary osmolality did not.
Shimura concluded that a simple water deprivation test incorporating measurements of urine AVP concentration and urinary osmolality was a simple, accurate way to distinguish NDI patients from CCDI and ICDI patients. It also could distinguish all three categories from people without these disorders and patients with polyuria and polydipsia due to some other causes.