J Med Cases

Journal of Medical Cases, ISSN 1923-4155 print, 1923-4163 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Med Cases and Elmer Press Inc

Journal website https://jmc.elmerpub.com

Case Report

Volume 17, Number 9, September 2026, pages 464-469

The Hidden Link: Cryoglobulinemic Membranoproliferative Glomerulonephritis Secondary to Monoclonal Gammopathy of Renal Significance

↓ Figure 2. IgG immunofluorescence (yellow arrows) indicating cryoglobulinemic glomerulonephritis. Ig: immunoglobulin.

↓ **Table 1.** CBC, CMP and Iron Studies
Serum	Patient values	Reference range
CBC: complete blood count; CMP: comprehensive metabolic panel; ALT: alanine aminotransferase; AST: aspartate aminotransferase; eGFR: estimated glomerular filtration rate; TIBC: total iron-binding capacity; BUN: blood urea nitrogen; WBC: white blood cell.
WBC count	4.87	4,000–11,000
Hemoglobin	11.5	12.0–15.5 g/dL
Platelet count	303	150,000–450,000/µL
Anion gap	10.5	4–12 mEq/L
Sodium	141	135–145 mEq/L
Potassium	5.2	3.6–5.2 mEq/L
Chloride	105	96-106 mEq/L
CO₂	25.4	23–29 mmol/L
Calcium level	9.8	8.5–10.5 mg/dL
BUN	35.6	6–20 mg/dL
Creatinine	1.7	0.5–1.1 mg/dL
Glucose	63	70–99 mg/dL
Protein	6.8	6.0–8.3 g/dL
Albumin	4.4	3.4–5.4 g/dL
Globulin	2.5	2.0–3.5 g/dL
ALT	19	4–36 U/L
AST	22	8–33 U/L
Alkaline phosphatase	84	44–147 IU/L
Bilirubin total	0.9	0.1–1.2 mg/dL
eGFR	33	> 90
Ferritin	95.9	30–400 ng/mL
Iron	63	50–170 µg/dL
TIBC	300	149–492 µg/dL
Transferrin	214	250–450 µg/dL

↓ Table 1. CBC, CMP and Iron Studies

Serum

Patient values

Reference range

CBC: complete blood count; CMP: comprehensive metabolic panel; ALT: alanine aminotransferase; AST: aspartate aminotransferase; eGFR: estimated glomerular filtration rate; TIBC: total iron-binding capacity; BUN: blood urea nitrogen; WBC: white blood cell.

WBC count

4.87

4,000–11,000

Hemoglobin

11.5

12.0–15.5 g/dL

Platelet count

303

150,000–450,000/µL

Anion gap

10.5

4–12 mEq/L

Sodium

141

135–145 mEq/L

Potassium

5.2

3.6–5.2 mEq/L

Chloride

105

96-106 mEq/L

CO₂

25.4

23–29 mmol/L

Calcium level

9.8

8.5–10.5 mg/dL

BUN

35.6

6–20 mg/dL

Creatinine

1.7

0.5–1.1 mg/dL

Glucose

70–99 mg/dL

Protein

6.8

6.0–8.3 g/dL

Albumin

4.4

3.4–5.4 g/dL

Globulin

2.5

2.0–3.5 g/dL

ALT

4–36 U/L

AST

8–33 U/L

Alkaline phosphatase

44–147 IU/L

Bilirubin total

0.9

0.1–1.2 mg/dL

eGFR

> 90

Ferritin

95.9

30–400 ng/mL

Iron

50–170 µg/dL

TIBC

300

149–492 µg/dL

Transferrin

214

250–450 µg/dL

↓ **Table 2.** Urine Studies
Urine	Patient values	Reference range
UA: urinalysis; RBC: red blood cell; HPF: high-power field.
UA color	Yellow	Clear to pale yellow
UA appearance	Clear	Clear
UA PH	5	4.6–8.0
UA specific gravity	1.013	1.005–1.030
UA bilirubin	Negative	Negative
UA blood	Trace	0–2 RBCs/HPF
UA glucose	250	0–0.8 mmol/L
UA ketones	Negative	< 0.6 mmol/L
UA leukocyte esterase	Trace	Negative
UA nitrite	Negative	Negative
UA protein	Trace	150 mg/day
UA urobilinogen	0.2	UA urobilinogen
Urine creatinine	60.1	0.8–2.0 g/day
Urine microalbumin/creatinine ratio	191	< below 30 mg/g
Urine microalbumin	11.5	< 30 mg/day
Urine protein	23.2	< 150 mg/day
Urine protein/creatinine ratio	0.38	< 0.2 mg/mg

↓ Table 2. Urine Studies

Urine

Patient values

Reference range

UA: urinalysis; RBC: red blood cell; HPF: high-power field.

UA color

Yellow

Clear to pale yellow

UA appearance

Clear

UA PH

4.6–8.0

UA specific gravity

1.013

1.005–1.030

UA bilirubin

Negative

UA blood

Trace

0–2 RBCs/HPF

UA glucose

250

0–0.8 mmol/L

UA ketones

Negative

< 0.6 mmol/L

UA leukocyte esterase

Trace

Negative

UA nitrite

Negative

UA protein

Trace

150 mg/day

UA urobilinogen

0.2

UA urobilinogen

Urine creatinine

60.1

0.8–2.0 g/day

Urine microalbumin/creatinine ratio

191

< below 30 mg/g

Urine microalbumin

11.5

< 30 mg/day

Urine protein

23.2

< 150 mg/day

Urine protein/creatinine ratio

0.38

< 0.2 mg/mg

↓ **Table 3.** Protein Electrophoresis
Serum	Patient values	Reference range
Kappa free light chain	10.37	3.3–19.4 mg/L
Lambda free light chain	1.75	5.7–26.3 mg/L
Kappa/lambda FLC ratio	5.93	0.26–1.65
Calculated albumin	4.28	3.5–5.0 g/dL
Urine protein electrophoresis	No Bence jones proteins	Albumin

↓ Table 3. Protein Electrophoresis

Serum

Patient values

Reference range

Kappa free light chain

10.37

3.3–19.4 mg/L

Lambda free light chain

1.75

5.7–26.3 mg/L

Kappa/lambda FLC ratio

5.93

0.26–1.65

Calculated albumin

4.28

3.5–5.0 g/dL

Urine protein electrophoresis

No Bence jones proteins

Albumin

↓ **Table 4.** Autoimmune Workup
Serum	Patient values	Reference range
ANA: antinuclear antibody; Ig: immunoglobulin.
ANA screen	Negative	Negative
Glomerular basement membrane IgG	Negative	< 7.0 U/mL
Myeloperoxidase antibody	Negative	< 0.4 U
Proteinase 3	Negative	< 2 IU/mL
Quantitative rheumatoid arthritis factor	< 10	< 14 IU/mL
C3 complement	76.8	88–201 mg/dL
C4 complement	13.7	15–45 mg/dL
IgA	82.9	70–400 mg/dL
IgG	1,042.00	600–1,600 mg/dL
IgM	333	40–250 mg/dL

↓ Table 4. Autoimmune Workup

Serum

Patient values

Reference range

ANA: antinuclear antibody; Ig: immunoglobulin.

ANA screen

Negative

Glomerular basement membrane IgG

Negative

< 7.0 U/mL

Myeloperoxidase antibody

Negative

< 0.4 U

Proteinase 3

Negative

< 2 IU/mL

Quantitative rheumatoid arthritis factor

< 10

< 14 IU/mL

C3 complement

76.8

88–201 mg/dL

C4 complement

13.7

15–45 mg/dL

IgA

82.9

70–400 mg/dL

IgG

1,042.00

600–1,600 mg/dL

IgM

333

40–250 mg/dL