Toxic Nephropathy Secondary to Chronic Mercury Poisoning: Clinical Characteristics and Outcomes

Abstract

Introduction: Kidney disease secondary to mercury poisoning has not been well documented and is often misdiagnosed and mistreated.

Methods: We performed a retrospective analysis of patients diagnosed with having mercury poisoning over a 6-year period between July 2013 and June 2019. Demographics, clinical measures, renal pathologic examinations, treatments, and outcomes were compared between patients with kidney disease and those without kidney disease.

Results: Of the 172 patients with mercury poisoning, 46 (26.74%) had renal damage. Among the 46 patients, 41 (89.13%) presented nephrotic syndrome, and 5 (10.87%) showed proteinuria alone. The pathologic abnormality associated with kidney disease caused by mercury poisoning was mainly membranous nephropathy (18 of 35 patients, 51.43%). Among 41 patients with nephrotic syndrome, 25 were treated with chelation therapy alone and 12 with mercury chelation therapy and glucocorticoids. The remaining 4 patients were treated with chelation therapy, glucocorticoids, and immunosuppressive therapies. The overall effective rate was 97.5% (40 patients). There was no significant difference in complete remission rate among the 3 treatment methods (P < 0.05).

Conclusion: The main clinical manifestation of kidney disease secondary to chronic mercury poisoning was nephrotic syndrome, which was reflected in pathologic examinations as membranous nephropathy. Kidney disease to chronic mercury poisoning is prone to misdiagnosis and missed diagnosis. Chelation therapy is the main treatment, and the prognosis is good. Patients with severe condition can be supplemented with glucocorticoid.

Keywords: clinical features; diagnosis and treatment; kidney disease; mercury poisoning.

Graphical abstract

Figure 1

Functional and structural criteria for kidney diseases and disorders. AKD, acute kidney disease; AKI, acute kidney injury; CKD, chronic kidney disease; GFR, glomerular filtration rate; NKD, no kidney disease; SCr, serum creatinine.

Figure 2

Representative images from a case of membranous nephropathy (a and b) and minimal-change disease (c and d) from patients with chronic mercury poisoning. (a) Glomerulus with thickened capillary loops. (b) Small subepithelial immune complex deposits. (c) Unremarkable glomerulus. (d) Global podocyte foot process effacement.