Division of Nephrology, Manipal Hospital, Visakhapatnam, Andhra Pradesh, India
1Department of Vital Care, Manipal Hospital, Visakhapatnam, Andhra Pradesh, India
Division of Nephrology, Manipal Hospital, Visakhapatnam, Andhra Pradesh, India
Summary
Introduction
Many substances are recognized to intrude with the most typical methodology used to estimate serum creatinine, i.e., Jaffe assay. Nitromethane, which is a well-liked solvent in natural business, is thought to trigger an identical impact.[1,2] We report one such uncommon case with spurious elevation in serum creatinine secondary to chemical publicity at office.
Case Report
A 25-year-old male introduced with complaints of dizziness and three episodes of generalized seizures. He had these signs after returning dwelling from a full day’s work at an natural manufacturing facility. There was no historical past of swelling of ft or face and breathlessness, fever, nausea, vomiting, or diarrhea. There was no oliguria, dysuria, pyuria, hematuria, or graveluria. No historical past was suggestive of any connective tissue dysfunction. There was no previous painkiller or native medication consumption.
On examination, the affected person was irritable with blood strain of 131/86 mm Hg with no proof of edema or pallor. Biochemical evaluation revealed elevated serum creatinine of 61 mg/dl, serum urea of seven mg/dl, and random blood sugar of 141 mg/dl with regular serum electrolytes. Hemogram was suggestive of raised complete leukocyte rely at 18000/mcl with predominance of neutrophils, regular hemoglobin, and platelet rely. Liver perform checks had been regular. Serum bicarbonate degree was 24.5 mmol/l. Viral markers had been adverse. Urine examination was suggestive of traces of protein, nil glucose, with 2–4 pus cells and no purple blood cells. As a result of discrepancy in laboratory reviews with regular blood urea and raised serum creatinine, a portion of blood pattern collected at evening was preserved in commonplace circumstances for additional evaluation. In view of raised serum creatinine and historical past of seizures, uremic encephalopathy was suspected, and the affected person was began on hemodialysis through femoral catheter entry. He was given parenteral anticonvulsants for seizures. Ultrasonogram of the stomach revealed bilateral normal-sized kidneys with regular echotexture. Roentgenogram of chest was regular. Plain computed tomography of mind was regular. Blood and urine cultures had been sterile. Serum creatine phosphokinase and lactate dehydrogenase ranges had been regular at 213 IU/L and 140 IU/L, respectively. His urine output was maintained at 1–1.5 L/day all through the hospital keep.
Enquiry of affected person’s kin and his employers on the manufacturing facility for attainable toxin publicity revealed utilization of nitromethane gasoline on the workstation of the affected person Preserved blood pattern was despatched for estimation of serum cystatin-C and enzymatic estimation of serum creatinine on the second day of admission. The values had been 0.69 mg/L (0.60 to 1.03 mg/L) and 0.9 mg/dl (0.6 to 1.4 mg/dl), respectively. After two hemodialysis periods, on the 4th day of admission, affected person’s blood pattern was resent for serum creatinine estimation by Jaffe’s assay and enzymatic methodology. Ranges had been 7.8 mg/dl by Jaffe assay and 0.7 mg/dl by enzymatic methodology. This confirmed our suspicion of false-positive elevation in serum creatinine. Nitromethane ranges couldn’t be estimated in serum on account of nonavailability of gasoline chromatography approach.
Serum creatinine degree on the seventh day of admission by Jaffe’s approach was 0.8 mg/dl. He was discharged in a steady situation on antiepileptics on the recommendation of neurologist. Assessment after 2 weeks in OPD revealed a steady affected person with serum creatinine of 0.9 mg/dl with no complaints. He was weaned off antiepileptics at 4 weeks of discharge.
Dialogue
A number of compounds may cause a false-positive response with Jaffe assay. They embody acetoacetate, cephalosporin, bilirubin, ascorbic acid, pyruvate, and dopamine. Discrepancy of reviews within the type of raised serum creatinine with regular blood urea ought to elevate suspicion of a attainable laboratory error.
Circumstances related to remoted elevate in serum creatinine embody these with decreased creatinine secretion, interference with the serum assay, or enhanced creatinine manufacturing.[3] Medicine similar to cimetidine, trimethoprim, and fibric acid derivatives competitively inhibit creatinine secretion and lift serum creatinine focus, regardless of having no impact on glomerular filtration charge. Increased muscle mass, ingestion of cooked meat, and circumstances related to rhabdomyolysis, for instance, hypothyroidism trigger an elevated technology of creatinine, thus elevating the blood degree.
Nitromethane is an natural compound with the chemical formulation CH3NO2. It’s a standard solvent in natural and electroanalytical chemistry. It interferes with colorimetric assay for the estimation of serum creatinine, i.e., Jaffe response. These assays contain the interplay of creatinine with alkaline picrate and subsequent monitoring of adjustments in absorbance between 500 nm and 530 nm. Nitromethane comprises a reactive methyl group, which reacts with alkaline picrate to provide a chromophore with a sample of absorbance throughout the spectrum that intently resembles the creatinine–picrate advanced [Figure 1], making a falsely elevated creatinine degree.[4] Research present that 1 mmol/l of nitromethane causes a 7.1 mg/dl rise in serum creatinine. Enzymatic assay of creatinine, whereas not as broadly used because the Jaffe response, renders correct measurement of creatinine within the presence of nitromethane. Intensive literature search couldn’t reveal any info relating to the dialysability of this chemical.
In our case, the affected person was uncovered to fumes of nitromethane on the natural manufacturing facility whereas cleansing the boiler. This led to central nervous system toxicity of this chemical within the type of seizures, which had been later managed with antiepileptics. The false rise in serum creatinine on account of absorption of toxin into blood resulted in pointless intervention within the type of central line cannulation and hemodialysis.[5]
Conclusion – “creatinine 0.9 mg dl”
Nitromethane is often used as a solvent in a wide range of industrial functions. Its interference with Jaffe assay results in a false elevation in serum creatinine and doesn’t point out renal dysfunction. The idea of false elevations in renal parameters must be thought-about in instances the place the scientific options and/or different parameters don’t correlate with renal dysfunction. Regular blood urea degree, if current, is a comfortable clue to falsely elevated serum creatinine. That is in all probability the primary case of its type reported from our nation.
References
Codecs:
“creatinine 0.9 mg dl”