UNASSIGNED: Paraproteins can interfere with several substances, producing erroneous laboratory measurements. The diagnosis of kidney disease in patients with hematological disorders has important prognosis implications. An elevated creatinine with no other signs of kidney disease should prompt the idea of a spurious creatinine. Communication between the clinical team and the laboratory is key.
UNASSIGNED: In this case, we present a 68-year-old woman with an elevated creatinine and an IgM lambda paraprotein. Interestingly, there were no other signs of chronic kidney disease besides the creatinine value, with no albuminuria or microhematuria. A kidney biopsy showed normal parenchyma and ruled out the possibility of paraprotein-related damage. The monoclonal component and creatinine levels raised parallelly during follow-up while maintaining normal urea levels. This prompted the hypothesis of a falsely elevated creatinine. It was confirmed with a normal glomerular filtration rate determined by a radioisotope, a cystatin C measurement and a reduction in creatinine when diluting the sample.
UNASSIGNED: It is important to consider the possibility of a falsely elevated creatinine in patients with paraproteinemia and no other signs of kidney disease to avoid unnecessary diagnostic tests and for the prognostic implications.

UNASSIGNED: Nitromethane is a primary nitroalkane used as a solvent and a fuel that may be toxic by ingestion, inhalation, or contact. Its presence can be detected in serum of exposed persons, but levels are not readily available to guide patient care. Nitromethane has been shown to falsely elevate serum creatinine when clinical laboratories use Jaffe assays to measure creatinine; enzymatic assays are not affected. Ex vivo experiments have demonstrated a linear relationship between serum nitromethane and the elevation in Jaffe assay creatinine. This case report demonstrates an elevation of creatinine measured by Jaffe assay with normal creatinine measurement by enzymatic assay after exposure to nitromethane.
UNASSIGNED: A 21-month-old girl ingested an unmeasured quantity of a hobby fuel, a fuel containing methanol, nitromethane (20%), and lubricants used in miniature internal combustion engines, such as remote-controlled cars. She was initially evaluated at a community hospital, treated empirically for methanol toxicity with fomepizole and folic acid, and transferred to a university hospital for further management. By 19 hours after ingestion, methanol was below detection, but a serum creatinine of 2.63 mg/dl raised concern for kidney injury. Toxicology consultation recognized that the creatinine had been measured using a Jaffe assay and recommended a repeat creatinine using an enzymatic assay, which was within normal limits. The patient remained an inpatient for further evaluation, which permitted trending of her Jaffe assay creatinine over a 3-day period. The Jaffe assay creatinine demonstrated a gradual decline; repeat enzymatic assay creatinine remained within normal limits.
UNASSIGNED: The decline in this pediatric patient\'s Jaffe assay creatinine is consistent with first-order clearance of nitromethane, which has been previously described in adult exposures. This case demonstrates how Jaffe assay-derived serum creatinine may be useful in the pediatric population to establish, quantify, and trend nitromethane exposure with essential concurrent use of an enzymatic assay to determine actual creatinine.

Transdermal absorption of isopropyl alcohol (IPA) can cause toxicity at high doses, but case reports of this phenomenon are limited. This is a single patient encounter and chart review describing a 33-year-old previously healthy female who presented obtunded, wrapped in IPA soaked round cotton pads with overlying shrink wrap, her family\'s home remedy for a mild persistent rash. This case highlights several interesting aspects of IPA toxicity, including evidence that toxic doses of IPA are possible through transdermal absorption and creatinine may be falsely elevated due to acetone\'s interference with the measurement of creatinine on some assays.