title: Asymptomatic elevation of creatine kinase in patients with hyponatremia.
abstract: Elevated creatine kinase (hyper-CKemia) has been observed in small number of patients with hyponatremia. This study evaluated the features and outcomes of patients admitted with hyponatremia complicated by hyper-CKemia. Patients admitted with hyponatremia and concurrently found to have elevated creatine kinase (CK) of above 375 IU/L (male) or 225 IU/L (female), over a 5-year period were retrospectively reviewed. Those with myocardial injury (elevated CK-MB isoenzyme [CK-MB/CK percentage of >2.5%] or Troponin T [>0.02 μg/L]), traumatic or ischemic muscle damage, primary myopathic disorder, seizures prior to CK measurement or those taking medications which can cause myopathy, were excluded. Thirty-two patients with hyponatremia and hyper-CKemia were identified. All patients had no muscular symptoms or weakness. The commonest cause of hyponatremia in this cohort was related to diuretics (50%). The mean sodium level on presentation was 116.0 ± 6.9 mmol/L and the median peak CK was 895.5 (interquartile range: 610.8-1691.8) IU/L. Six (18%) patients developed acute kidney injury (AKI). The length of hospital admission of the entire cohort was 8.0 ± 5.8 days. Patients with hyper-CKemia in the setting of diuretic-associated hyponatremia were older and had longer hospital length of stay compared with primary-polydipsia-associated. Asymptomatic hyper-CKemia is an uncommon association with hyponatremia of various etiologies. Hyponatremia-associated hyper-CKemia can be complicated by AKI.
authors.affiliation: Department of General Medicine, Flinders Medical Centre , Adelaide , Australia .
authors.forename: Kareeann S F
authors.initials: KS
authors.lastname: Khow
authors.forename: Su Y
authors.initials: SY
authors.lastname: Lau
authors.forename: Jordan Y Z
authors.initials: JY
authors.lastname: Li
authors.forename: Tuck Y
authors.initials: TY
authors.lastname: Yong
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood / Q000209:etiology; D000368:Aged; D000369:Aged, 80 and over; D003402:Creatine Kinase / Q000097:blood*; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000150:complications*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D003402:Creatine Kinase
keywords: Creatine kinase; diuretic; hyper-CKemia; hyponatremia; polydipsia