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Clinical laboratory evaluation of the syndrome of inappropriate secretion of antidiuretic hormone
- Source :
- Clinical journal of the American Society of Nephrology : CJASN. 3(4)
- Publication Year :
- 2008
-
Abstract
- Hyponatremia secondary to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a frequent cause of hypotonicity. Although the differential diagnosis with other causes of hypotonicity such as salt depletion is sometimes challenging, some simple and readily available biologic parameters can be helpful in the diagnosis of SIADH. In SIADH, urea is typically low; this is less specific for elderly patients, for whom lower clearance of urea accounts for higher values. Low levels of uric acid are more often seen in SIADH (70%) compared with salt-depleted patients (40%). Typically, patients with SIADH will show a lower anion gap with nearly normal total CO2 and serum potassium, this despite dilution. In patients with hyponatremia secondary to hypocorticism, total CO2 is usually lower than in nonendocrine SIADH despite low urea and uric acid levels. Urine biology can also be helpful in diagnosis of SIADH because patients with SIADH have high urine sodium (Na; >30 mEq/L), and most of them will have a high fractional excretion of Na (>0.5% in 70% of cases), reflecting salt intake. Conversely, low urine Na in patients with SIADH and poor alimentation is not rare. Finally, measurement of urine osmolality is useful for the diagnosis of polydipsia and reset osmostat and could further help in the choice of therapeutic strategy because patients with low urine osmolality will benefit from water restriction or urea, whereas those with high urine osmolality (>600 mOsm/kg) would be good candidates for V2 antagonist.
- Subjects :
- Erythrocyte Indices
medicine.medical_specialty
Epidemiology
Anion gap
Urine
Osmostat
Critical Care and Intensive Care Medicine
Urine sodium
Excretion
Diagnosis, Differential
Inappropriate ADH Syndrome
Internal medicine
medicine
Humans
Urea
Salt intake
Serum Albumin
Acid-Base Equilibrium
Transplantation
business.industry
Clinical Laboratory Techniques
Diagnostic Tests, Routine
Osmolar Concentration
Sodium
medicine.disease
Uric Acid
Bicarbonates
Endocrinology
Hematocrit
Nephrology
Creatinine
Urine osmolality
Potassium
Hyponatremia
business
Biomarkers
Subjects
Details
- ISSN :
- 1555905X
- Volume :
- 3
- Issue :
- 4
- Database :
- OpenAIRE
- Journal :
- Clinical journal of the American Society of Nephrology : CJASN
- Accession number :
- edsair.doi.dedup.....c3f84461cc7bc7271ffc2ceb3a6e367a