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 12, December 2026, pages 707-711

The Vitamin B12–C-Reactive Protein Index in Advanced Cancer: A Case Report and Narrative Review of an Underutilized Potential Prognostic Biomarker

↓ **Table 1.** Summary of Key Clinical and Laboratory Data
Parameter	Result	Stated reference range or threshold	Classification
^aThe reported vitamin B9 result (“> 20.0 ng/mL”) does not establish whether the true value exceeds the upper reference limit of 32.2 ng/mL; it cannot reliably be classified as within range or increased. ^bThe HbA1c threshold of < 7% appears to be a treatment target, not a laboratory reference range. Confirm the laboratory’s actual reference interval before classifying HbA1c as “within range.” BCI: B12–CRP index; CRP: C-reactive protein; AFP: alpha-fetoprotein; CEA: carcinoembryonic antigen; ALP: alkaline phosphatase; GGT: gamma-glutamyl transferase; AST: aspartate aminotransferase; ALT: alanine aminotransferase; HbA1c: glycated hemoglobin; CKD-EPI: Chronic Kidney Disease Epidemiology Collaboration.
Hemoglobin	10.2 g/dL	13.4–16.7 g/dL	Decreased
Mean corpuscular volume	101.9 fL	82.1–97 fL	Increased
White blood cells	16.12 G/L	4.05–9.92 G/L	Increased
Neutrophils	13.34 G/L	1.85–6.14 G/L	Increased
Platelets	131 G/L	161–393 G/L	Decreased
Albumin	30 g/L	35–52 g/L	Decreased
CRP	16.8 mg/L	< 5 mg/L	Increased
Vitamin B12	1,126 pmol/L	190–790 pg/mL	Increased
BCI	18,917	No established reference range	Not classified
Vitamin B9^a	> 20.0 ng/mL	4.5–32.2 ng/mL
Corrected calcium	2.80 mmol/L	2.20–2.55 mmol/L	Increased
AFP	14,756 ng/mL	< 7 ng/mL	Increased
CEA	18.5 µg/L	< 5 µg/L	Increased
ALP	342 U/L	35–105 U/L	Increased
GGT	612 U/L	< 60 U/L	Increased
AST	129 U/L	< 51 U/L	Increased
ALT	37 U/L	< 51 U/L	Within range
Total bilirubin	26.6 mg/L	< 15 mg/L	Increased
Prothrombin time	68%	70–100%	Decreased
Creatinine	115.9 µmol/L	59.3–103.5 µmol/L	Increased
Estimated glomerular filtration rate (CKD-EPI)	57.1 mL/min/1.73 m²	> 90 mL/min/1.73 m²	Decreased
Serum sodium	137 mmol/L	136–145 mmol/L	Within range
Serum potassium	4.1 mmol/L	3.6–4.6 mmol/L	Within range
HbA1c^b	4.3%	< 7%	Below stated threshold

↓ Table 1. Summary of Key Clinical and Laboratory Data

Parameter

Result

Stated reference range or threshold

Classification

^aThe reported vitamin B9 result (“> 20.0 ng/mL”) does not establish whether the true value exceeds the upper reference limit of 32.2 ng/mL; it cannot reliably be classified as within range or increased. ^bThe HbA1c threshold of < 7% appears to be a treatment target, not a laboratory reference range. Confirm the laboratory’s actual reference interval before classifying HbA1c as “within range.” BCI: B12–CRP index; CRP: C-reactive protein; AFP: alpha-fetoprotein; CEA: carcinoembryonic antigen; ALP: alkaline phosphatase; GGT: gamma-glutamyl transferase; AST: aspartate aminotransferase; ALT: alanine aminotransferase; HbA1c: glycated hemoglobin; CKD-EPI: Chronic Kidney Disease Epidemiology Collaboration.

Hemoglobin

10.2 g/dL

13.4–16.7 g/dL

Decreased

Mean corpuscular volume

101.9 fL

82.1–97 fL

Increased

White blood cells

16.12 G/L

4.05–9.92 G/L

Increased

Neutrophils

13.34 G/L

1.85–6.14 G/L

Increased

Platelets

131 G/L

161–393 G/L

Decreased

Albumin

30 g/L

35–52 g/L

Decreased

CRP

16.8 mg/L

< 5 mg/L

Increased

Vitamin B12

1,126 pmol/L

190–790 pg/mL

Increased

BCI

18,917

No established reference range

Not classified

Vitamin B9^a

> 20.0 ng/mL

4.5–32.2 ng/mL

Corrected calcium

2.80 mmol/L

2.20–2.55 mmol/L

Increased

AFP

14,756 ng/mL

< 7 ng/mL

Increased

CEA

18.5 µg/L

< 5 µg/L

Increased

ALP

342 U/L

35–105 U/L

Increased

GGT

612 U/L

< 60 U/L

Increased

AST

129 U/L

< 51 U/L

Increased

ALT

37 U/L

< 51 U/L

Within range

Total bilirubin

26.6 mg/L

< 15 mg/L

Increased

Prothrombin time

68%

70–100%

Decreased

Creatinine

115.9 µmol/L

59.3–103.5 µmol/L

Increased

Estimated glomerular filtration rate (CKD-EPI)

57.1 mL/min/1.73 m²

> 90 mL/min/1.73 m²

Decreased

Serum sodium

137 mmol/L

136–145 mmol/L

Within range

Serum potassium

4.1 mmol/L

3.6–4.6 mmol/L

Within range

HbA1c^b

4.3%

< 7%

Below stated threshold

↓ **Table 2.** Comparison of the Main Prognostic Scores
Score	Variables	Laboratory variables included	Time to completion	Validation	Main purpose	Limitations
PPS: Palliative Performance Scale; PPI: Palliative Prognostic Index; PaP Score: Palliative Prognostic Score; mGPS: modified Glasgow Prognostic Score; CAR: C-reactive protein/albumin ratio.
PPS	Mobility, autonomy, nutrition, consciousness	None	< 2 min	+++	Simple clinical assessment	Subjective
PPI [13]	PPS, edema, dyspnea, anorexia, delirium	None	5 min	+++	Survival at 3–6 weeks	Depends on the clinical examination
PaP Score [14]	Performance, anorexia, dyspnea, white blood cells, lymphocytes, clinician’s assessment	White blood cell count and lymphocyte percentage	10 min	+++	30-day survival	Requires laboratory results, a clinician’s survival prediction, and assignment of weighted points to six variables
mGPS [15]	CRP + albumin	CRP and albumin	Immediate	++++	Systemic inflammation	Does not take function into account
CAR [16]	CRP/albumin	CRP and albumin	Immediate	++++	Very good prognostic value	Not very specific
BCI [9, 17]	Vitamin B12 × CRP	Vitamin B12 and CRP	Immediate	++	Tumor burden + inflammation	Few studies, limited external validation

↓ Table 2. Comparison of the Main Prognostic Scores

Score

Variables

Laboratory variables included

Time to completion

Validation

Main purpose

Limitations

PPS: Palliative Performance Scale; PPI: Palliative Prognostic Index; PaP Score: Palliative Prognostic Score; mGPS: modified Glasgow Prognostic Score; CAR: C-reactive protein/albumin ratio.

PPS

Mobility, autonomy, nutrition, consciousness

None

< 2 min

+++

Simple clinical assessment

Subjective

PPI [13]

PPS, edema, dyspnea, anorexia, delirium

None

5 min

+++

Survival at 3–6 weeks

Depends on the clinical examination

PaP Score [14]

Performance, anorexia, dyspnea, white blood cells, lymphocytes, clinician’s assessment

White blood cell count and lymphocyte percentage

10 min

+++

30-day survival

Requires laboratory results, a clinician’s survival prediction, and assignment of weighted points to six variables

mGPS [15]

CRP + albumin

CRP and albumin

Immediate

++++

Systemic inflammation

Does not take function into account

CAR [16]

CRP/albumin

CRP and albumin

Immediate

++++

Very good prognostic value

Not very specific

BCI [9, 17]

Vitamin B12 × CRP

Vitamin B12 and CRP

Immediate

Tumor burden + inflammation

Few studies, limited external validation