# A Series of Eight Cases of Pigment Nephropathy: An Obscured Aspect of Acute Kidney Injury

## TL;DR

This paper reports eight cases of acute kidney injury caused by pigment buildup from rhabdomyolysis or hemolysis, emphasizing the importance of early diagnosis and treatment.

## Contribution

The study highlights pigment nephropathy as an under-recognized cause of acute kidney injury through detailed case reporting.

## Key findings

- Eight cases of pigment-induced AKI were identified, with six due to myoglobin and two due to hemoglobin.
- Seven patients required dialysis due to severe renal failure.
- Short-term recovery was favorable, but long-term effects remain uncertain.

## Abstract

Pigment-induced acute kidney injury (AKI) is an important and preventable complication of rhabdomyolysis or hemolysis. It is characterized by the release of free heme pigment (myoglobin or hemoglobin) in the circulation, leading to direct injury of the proximal tubule and distal tubule obstruction by pigment cast. We are reporting eight cases of pigment-induced AKI, including six cases of myoglobin cast nephropathy and two cases of hemoglobin cast nephropathy. The causes of rhabdomyolysis were strenuous exercise, infection/febrile illness, and drug-induced neuroleptic malignant syndrome. Paroxysmal nocturnal hemoglobinuria and anti-tuberculosis treatment (rifampicin and isoniazid) had led to hemoglobin cast nephropathy each in one case. Seven cases had severe renal failure requiring dialysis. Short-term renal outcome was favorable. However, long-term follow-up is necessary to determine whether pigment-induced AKI has delayed sequelae. Therefore, clinicians should consider rhabdomyolysis or hemolysis as potential hidden causes of AKI in diverse clinical conditions, especially those of non-traumatic origin, to achieve an accurate diagnosis.