Reevaluation of the criteria for the clinical diagnosis of Gitelman syndrome.
A 16-year-old female had mutations in both alleles of the gene encoding her sodium-chloride cotransporter; one of these mutations is newly described. Her clinical findings were not typical because of the absence of hypocalciuria in 24-h urine samples, her maximum urine osmolality (U(osm)) was only 802 mosmol/kg H(2)O, and her plasma magnesium (Mg) concentration (P(Mg)) was easily maintained in the normal range with oral Mg supplements for 1 month. In detailed studies, the calcium/creatinine ratio in spot urines with a U(osm) >700 mosmol/kg H(2)O was very low, except during Mg therapy. Renal medullary function did not appear to be compromised because she had a non-urea U(osm)of approximately 600 mosmol/kg H(2)O, reflecting a very high non-urea osmole excretion rate (due to KCl supplements). At age 18 years, her P(Mg) became persistently low despite Mg therapy. We conclude that the clinical criteria for a provisional diagnosis of Gitelman syndrome should be revised. Hypocalciuria may only be evident initially in concentrated spot urine samples. Urine concentrating ability should include an analysis of the non-urea U(osm), especially when patients are taking large KCl supplements.
Ring
Troels
T
Department of Nephrology, Aalborg Hospital, Aalborg, Denmark.
Knoers
Nine
N
Oh
Man S
MS
Halperin
Mitchell L
ML
D000293:Adolescent; D002352:Carrier Proteins / Q000235:genetics*; D002413:Cations, Divalent / Q000652:urine; D004247:DNA / Q000235:genetics; D004573:Electrolytes / Q000097:blood / Q000652:urine; D005260:Female; D006579:Heterozygote; D006801:Humans; D008275:Magnesium Deficiency / Q000097:blood / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D009994:Osmolar Concentration; D011955:Receptors, Drug; D049992:Sodium Chloride Symporters; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters / Q000235:genetics* / Q000378:metabolism*; D013577:Syndrome; D014563:Urodynamics / Q000502:physiology
D002352:Carrier Proteins; D002413:Cations, Divalent; D004573:Electrolytes; D011955:Receptors, Drug; C578874:SLC12A3 protein, human; D049992:Sodium Chloride Symporters; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters; C064415:thiazide receptor; D004247:DNA