From the Research
The specific gravity of urine is decreased in Diabetes Insipidus (DI) because the condition causes excessive water excretion without adequate concentration of urine, resulting from either insufficient production of antidiuretic hormone (ADH) or reduced kidney response to ADH, as noted in a study published in 2006 1. This condition can be life-threatening if not properly diagnosed and managed. The distinction between central and nephrogenic DI is essential for effective treatment.
- In DI, there is either insufficient production of antidiuretic hormone (ADH) by the hypothalamus (central DI) or reduced kidney response to ADH (nephrogenic DI).
- ADH normally signals the kidneys to reabsorb water and concentrate urine.
- Without proper ADH function, the kidneys cannot reabsorb water effectively from the collecting ducts, resulting in large volumes of dilute urine.
- This dilution leads to urine specific gravity readings typically below 1.005, compared to the normal range of 1.010-1.025, as discussed in a study from 2016 2. The excessive water loss also triggers intense thirst (polydipsia) as the body attempts to replace lost fluids.
- Treatment depends on the type of DI but may include desmopressin (DDAVP) for central DI, addressing underlying causes for nephrogenic DI, or thiazide diuretics which paradoxically reduce urine output in this condition by promoting proximal tubule water reabsorption, as supported by a case report from 2024 3. It's worth noting that the efficacy of desmopressin in nephrogenic DI remains unclear, but a recent case report suggests it can be a viable treatment option when used in combination with thiazide diuretics and non-steroidal anti-inflammatory drugs 3.