Adaptation of a Quantitative Immunoassay for Urine Myoglobin:Predictor in Detecting Renal Dysfunction

Abstract

A d a p t a t i o n o f a Q u a n t i t a t i v e I m m u n o a s s a y f o r U r i n e M y o g l o b i nThe authors describe the adaptation and optimization of the Stratus II serum myoglobin immunoassay to quantify urine myoglobin. In addition, the assay was used to accurately determine urine myoglobin concentrations in subjects at potential risk for myoglobin-induced renal dysfunction and the results obtained compared to conventional qualitative methods for urine myoglobin. The assay demonstrated with-in run and between-run coefficient of variations (CVs) of 6.2% and 7.2%., respectively, was linear from 0-950 jzg/L, demonstrated good recovery, and was free from interference by hemoglobin, creatinine, and urea. Specimens were diluted with 0.1 mol/L phosphate buffer, pH 9.0 containing 3% bovine serum albumin before analysis. Myoglobin was assayed on urine obtained from 30 patients suspected of having myoglobinuria. Fifteen of 17 patients with serum creatinine greater than 1.4 mg/dL had myoglobin concentrations greater than 20,000 ng/L, whereas the remaining 13 patients with normal serum creatinine had urine myoglobin concentrations of less than 18,000 Mg/L. If serum creatinine is used as an indicator of renal function, it would appear that accurate measurement of urine myoglobin may facilitate identification of patients with increased susceptibility to myoglobin-induced acute renal failure.

Utility of Urine Myoglobin for the Prediction of Acute Renal Failure in Patients with Suspected Rhabdomyolysis: A Systematic Review

“…These early methods took advantage of the pseudo-peroxidase activity of the heme moiety in myoglobin, but required complete removal of hemoglobin in the urine, which was difficult to achieve (3,9,10 ). The development of immunometric assays for myoglobin allowed more specific measurement and the potential for better predictive ability, such as in establishing a cutpoint for development of ARF (1,3,11 ). Despite this method development, the older, less-specific methods continue to be used.…”

“…The study designs included 32 case series , 16 cohort studies (11,(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59), and 4 case control studies (60 -63 ), for a total of 2399 subjects. Of the 52 studies, 16 measured uMb in only a portion of their study group.…”

“…Eighteen studies (35%) employed a colorimetric method, which usually involved a preseparation step by centrifugation or filtration to remove hemoglobin, followed by a commercial dipstick for hemoprotein (11, 14, 17, 26, 27, 29, 33-35, 38, 42, 45, 48, 52-54, 56, 57 ), and 19 (37%) used immunometric methods (11, 13, 18, 19, 23, 28, 31, 32, 38, 43, 44, 46, 47, 51, 58 -62 ). Two studies applied Ͼ1 method to detect or quantify uMb (11,38 ). Serum creatine kinase (CK), also increased in rhabdomyolysis, was measured in 38 studies (11, 13-28, 30 -34, 36 -38, 40 -45, 47, 52, 56, 57, 61-63 ), and of these, only 4 had extractable data comparing uMb with CK (45,47,51,59 ).…”

Speciation of magnesium in rat plasma using capillary electrophoresis‐inductively coupled plasma‐atomic emission spectrometry

“…Magnesium is the second most important intracellular cation after potassium and is found in all tissues. Magnesium stimulates bone growth and promotes the body's use of vitamins B, C, and E. It also plays a pivotal role in living beings and is vital in the biotope [3,4]. In human body, magnesium is present in various forms: as ionized, complexed, and protein bounded.…”

Crush injury and rhabdomyolysis

“…Of note, initial CK levels were not found to be predictive of renal dysfunction in this study. Another report found that elevated urine myoglobin levels greater than 20,000 ng/mL were associated with a significantly increased risk of renal dysfunction [106].…”