![]() The urine of DI has been classically described as insipid (tasteless), hypotonic and dilute ( 3). Large volumes of urine excretion, also known as polyuria (typically over 4 L per day), is the hallmark of DI. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, INTRODUCTIONĭiabetes insipidus (DI) is a disorder of water homeostasis that is characterized by excretion of large volumes of hypotonic urine either due to the deficiency of the hormone arginine vasopressin, or due to resistance to the action of AVP on its receptors in the kidneys ( 1, 2). This chapter describes the diagnostic steps to be pursued to identify the presence of DI, distinguish the various forms of polyuria-polydipsia disorders, identify the underlying disorders responsible for the DI, the challenges faced with diagnostic testing for DI in clinical practice, and future prospects in the field of DI diagnosis. ![]() Lastly, a detailed history and physical examination must be performed and appropriate laboratory and imaging studies must be undertaken to identify the underlying etiology of DI. This can be determined either through the water deprivation test or through the hypertonic saline infusion test along with plasma AVP or plasma copeptin measurements. Once hypotonic polyuria is established, the next step is to identify the type of polyuria-polydipsia disorder (central DI vs. When a case of DI is suspected, the initial step involves the confirmation of the presence of hypotonic polyuria, which is the hallmark of DI. This is mainly because the results obtained from diagnostic testing can show significant overlap among the different forms of DI and primary polydipsia. Like other endocrine disorders, an accurate diagnosis of DI can be challenging. Both DI and primary polydipsia are collectively referred to as ‘polyuria-polydipsia syndromes. A third condition called primary polydipsia can clinically show overlapping features with DI. In most circumstances, DI is also characterized by excessive consumption of water (polydipsia). The underlying cause is either a deficiency of the hormone arginine vasopressin (AVP) in the pituitary gland/hypothalamus (central DI), or resistance to the actions of AVP in the kidneys (nephrogenic DI). Result should be interpreted in conjunction with serum result.Diabetes insipidus (DI) is a disorder characterized by excretion of large volumes of hypotonic urine. Reference range for random urine not available. It is also used to monitor compliance with a low salt diet in hypertensive patients. A urinary sodium of 20mmol/L (typically >50mmol/L) in conjunction with a low/normal urea and/or urate is indicative of SIADH. Urinary sodium levels are also frequently ordered during the workup of acute renal failure with the fractional excretion of sodium used as an important marker in distinguishing pre-renal from post-renal failure. Urinary sodium, together with assessment of volume status, is useful in the differential diagnosis of hyponatramia. 24 hour container, urine monovette or white topped universal (no additives) TestĢ4 hour container, urine monovette or white topped universal (no additives)
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