Congophilic fibrils in the glomeruli with polyclonal immunoglobulin gamma staining - another cause for diagnostic overlap: A case report

Table 1 Laboratory results

Test	Result	Reference ranges
Hemoglobin, g/dL	8.4	13.8-17.2
White blood cell count, /μL	10000	4500-11000
Platelet count, K/μL	227000	150000-450000
Serum creatinine, mg/dL	8.1	0.72-1.25
eGFR, mL/min/1.73 m2	7	> 90
Calcium (total), mg/dL	8.0	8.4-10.2
Phosphorus, mg/dL	7.4	3.4-4.5
Serum C3, mg/dL	95	90-180
Serum C4, mg/dL	34	15-45

eGFR: Estimated glomerular filtration rate (calculated using the 2021 Chronic Kidney Disease Epidemiology Collaboration creatinine equation).

Table 2 Hematologic work-up for monoclonal gammopathy

	Serum assays performed at outside hospital	Reference range and units (in our institution)
Immunofixation, serum	Single spike-IgG lambda	Negative
Monoclonal protein 1 (mg/dL)	900	≤ 0.0
Monoclonal protein 2 (mg/dL)	Absent	≤ 0.0
Serum kappa free light chains (mg/L)	37.7	3.9-26.0
Serum lambda free light chains (mg/L)	366.3	6.4-22.1
Serum kappa:lambda ratio	0.10	0.51-1.72