{{Short description|Excretion of urine reflecting kidney damage}} {{cs1 config |display-authors=6 |name-list-style=vanc}} {{Use dmy dates|date=October 2025}} '''Isosthenuria''' refers to the excretion of urine whose specific gravity (concentration) is neither greater (more concentrated) nor less (more diluted) than that of protein-free plasma, typically 1.008-1.012.<ref>{{DorlandsDict|four/000055251|isosthenuria}}</ref> 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 "due to inability of the kidney to concentrate the urine normally".<ref>{{DorlandsDict|four/000051848|hyposthenuria}}</ref><ref>{{cite web |title=Medical Definition of HYPOSTHENURIA |url=https://www.merriam-webster.com/medical/hyposthenuria |access-date=2 February 2022 |publisher=Merriam-Webster |language=English}}</ref> This specific gravity is 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 kidney disease and acute kidney injury 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.<ref>{{cite book |last=De Mais |first=Daniel |title=ASCP Quick Compendium of Clinical Pathology |publisher=ASCP Press |year=2009 |edition=2nd |location=Chicago}}</ref>{{page needed|date=October 2025}}
Sickle-cell trait, the heterozygous form of sickle-cell disease, presents with a normal hematological picture but is associated with hyposthenuria.<ref>{{cite journal |vauthors=Gupta AK, Kirchner KA, Nicholson R, Adams JG 3rd, Schechter AN, Noguchi CT, Steinberg MH |year=1991 |title=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 |journal=J. Clin. Invest. |volume=88 |issue=6 |pages=1963–1968 |doi=10.1172/JCI115521 |pmc=295777 |pmid=1752955 |doi-access=free}}</ref>
==See also== * Hypersthenuria
==References== {{Reflist}}
{{Abnormal clinical and laboratory findings for urine}}
Category:Abnormal clinical and laboratory findings for urine
{{Med-sign-stub}}