Isosthenuria

Isosthenuria refers to the excretion of urine whose specific gravity (concentration) is neither greater (more concentrated) nor less (more dilute) than that of protein-free plasma, typically 1.008-1.012.[1] Isosthenuria reflects damage to the kidney's tubules or the renal medulla.

A closely related term is hyposthenuria, where the urine has a relatively low specific gravity,[2] though not necessarily equal to that of plasma. Therefore, unlike isosthenuria, this condition is not associated with kidney failure as the kidney tubules have altered the glomerular filtrate.

Clinical significance

Isosthenuria may be seen in disease states as chronic and acute kidney failure in which the kidneys lack the ability to concentrate or dilute the urine and so the initial filtrate of the blood remains unchanged despite the need to conserve or excrete water based on the body's hydration status.[3]

Sickle-cell trait, the heterozygous form of sickle-cell disease, presents with a normal hematological picture but is associated with hyposthenuria.[4]

See also

References
  1. "isosthenuria" at Dorland's Medical Dictionary
  2. "hyposthenuria" at Dorland's Medical Dictionary
  3. De Mais, Daniel. ASCP Quick Compendium of Clinical Pathology, 2nd Ed. ASCP Press, Chicago, 2009.
  4. Gupta AK, Kirchner KA, Nicholson R, et al. Effects of alpha-thalassemia and sickle polymerization tendency on the urine-concentrating defect of individuals with sickle cell trait and increased frequency of urinary tract infections J. Clin. Invest. Vol 88, Issue 6, pgs 1963-8. Dec 1991. PMID 1752955 PMC = 295777. DOI = 10.1172/JCI115521


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