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 000, Number 000, January 2026, pages 000-000

Intravenous Thiamine-Induced Thrombocytopenia in a Patient With Chronic Adrenal Insufficiency

**Table 1.** Baseline Laboratory Values (Day 0)
Parameter	Value	Reference range
WBC: white blood cell; MCV: mean corpuscular volume.
Hemoglobin	13.3 g/dL	12.5 - 16.5 g/dL
WBC	7.5 × 10⁹/L	4.0 - 11.0 × 10⁹/L
Platelets	225 × 10⁹/L	150 - 450 × 10⁹/L
MCV	96 fL	78 - 98 fL
Reticulocytes	1.2%	0.5-2.5%

Table 1. Baseline Laboratory Values (Day 0)

Parameter

Value

Reference range

WBC: white blood cell; MCV: mean corpuscular volume.

Hemoglobin

13.3 g/dL

12.5 - 16.5 g/dL

WBC

7.5 × 10⁹/L

4.0 - 11.0 × 10⁹/L

Platelets

225 × 10⁹/L

150 - 450 × 10⁹/L

MCV

96 fL

78 - 98 fL

Reticulocytes

1.2%

0.5-2.5%

**Table 2.** Platelet Count Timeline and Common Terminology Criteria for Adverse Events (CTCAE) Grading
Day	Intervention	Platelet count (× 10⁹/L)	% Change	CTCAE grade
0 (baseline)	Before thiamine (day of initiation)	225	0	0
1	Day 1 after thiamine started	150	-33%	0
2	Day 2 - thiamine continued	110	-51%	0
3	Day 3 - thiamine continued	86	-62%	Grade 1
4	Day 4 - thiamine continued	63	-72%	Grade 2
5	Day 5 - thiamine continued	48	-79%	Grade 3
6	Day 6 - thiamine stopped	65	+35%	Grade 2
7	Day 7 - post-cessation	88	+83%	Grade 2
8	Day 8 - post-cessation	132	+175%	Grade 1
14	Day 14 - follow-up (2 weeks)	265	Complete recovery	0

Table 2. Platelet Count Timeline and Common Terminology Criteria for Adverse Events (CTCAE) Grading

Day

Intervention

Platelet count (× 10⁹/L)

% Change

CTCAE grade

0 (baseline)

Before thiamine (day of initiation)

225

Day 1 after thiamine started

150

-33%

Day 2 - thiamine continued

110

-51%

Day 3 - thiamine continued

-62%

Grade 1

Day 4 - thiamine continued

-72%

Grade 2

Day 5 - thiamine continued

-79%

Grade 3

Day 6 - thiamine stopped

+35%

Grade 2

Day 7 - post-cessation

+83%

Grade 2

Day 8 - post-cessation

132

+175%

Grade 1

Day 14 - follow-up (2 weeks)

265

Complete recovery

**Table 3.** Systematic Exclusion of Alternative Causes
Condition	Investigations	Results	Conclusion
DIC: disseminated intravascular coagulation; HIT: heparin-induced thrombocytopenia; TTP: thrombotic thrombocytopenic purpura; HUS: hemolytic uremic syndrome; HIV: human immunodeficiency virus; Hep C: hepatitis C virus; Hep B: hepatitis B virus; RBC: red blood cell; CRP: C-reactive protein; PT: prothrombin time; aPTT: activated partial thromboplastin time; INR: international normalized ratio; ANA: antinuclear antibody; ESR: erythrocyte sedimentation rate; LDH: lactate dehydrogenase; CBC: complete blood count; HIV Ag/Ab test: human immunodeficiency virus antigen/antibody test; anti-HCV antibody: hepatitis C virus antibody; HBsAg: hepatitis B surface antigen; anti-HBc: hepatitis B core antibody; anti-HBs: hepatitis B surface antibody; AST: aspartate aminotransferase; ALT: alanine aminotransferase; GGT: gamma-glutamyl transferase.
Sepsis	Vitals, CRP, blood cultures	BP 135/88, CRP 0.88 mg/dL, cultures negative	Excluded
DIC	PT, aPTT, INR, fibrinogen, D-dimer	PT 10 s, aPTT 26 s, INR 0.9, Fib 360 mg/dL, D-dimer 0.50	Excluded
HIT	Heparin exposure, 4T score	No heparin exposure, 4T score = 0	Excluded
Autoimmune	ANA, Coombs, ESR	ANA negative, Coombs negative, ESR 18	Excluded
TTP/HUS	LDH, haptoglobin, schistocytes	LDH 160 IU/L, haptoglobin 52 mg/dL, no schistocytes	Excluded
Bone marrow	CBC, peripheral smear	Isolated thrombocytopenia, normal morphology	Excluded
HIV infection, Hep C, and Hep B	HIV Ag/Ab test, anti-HCV antibody, HBsAg, anti-HBc, and anti-HBs	Negative, negative, negative, negative, and positive	Excluded and vaccinated Hep B
Liver function test	AST, ALT, alkaline phosphatase, GGT, total bilirubin	34 U/L, 38 U/L, 56 U/L, 22U/L, 1.1 mg/dL	Normal test
Renal function and electrolytes	Creatinine, urea, Na, K, Cl, Mg, Ca	1.1 mg/dL, 22 mg/dL, 134 mmol/L, 3.7 mmol/L, 99 mmol/L, 1.9 mg/dL, 9.3 mg/dL	Borderline test
Vitamin B12 and folate	Serum values of vitamin B12 and folate	369 pmol/L, 14 ng/mL	Normal
RBC count	RBC count	5.1 × 10⁶/µL	Normal

Table 3. Systematic Exclusion of Alternative Causes

Condition

Investigations

Results

Conclusion

DIC: disseminated intravascular coagulation; HIT: heparin-induced thrombocytopenia; TTP: thrombotic thrombocytopenic purpura; HUS: hemolytic uremic syndrome; HIV: human immunodeficiency virus; Hep C: hepatitis C virus; Hep B: hepatitis B virus; RBC: red blood cell; CRP: C-reactive protein; PT: prothrombin time; aPTT: activated partial thromboplastin time; INR: international normalized ratio; ANA: antinuclear antibody; ESR: erythrocyte sedimentation rate; LDH: lactate dehydrogenase; CBC: complete blood count; HIV Ag/Ab test: human immunodeficiency virus antigen/antibody test; anti-HCV antibody: hepatitis C virus antibody; HBsAg: hepatitis B surface antigen; anti-HBc: hepatitis B core antibody; anti-HBs: hepatitis B surface antibody; AST: aspartate aminotransferase; ALT: alanine aminotransferase; GGT: gamma-glutamyl transferase.

Sepsis

Vitals, CRP, blood cultures

BP 135/88, CRP 0.88 mg/dL, cultures negative

Excluded

DIC

PT, aPTT, INR, fibrinogen, D-dimer

PT 10 s, aPTT 26 s, INR 0.9, Fib 360 mg/dL, D-dimer 0.50

Excluded

HIT

Heparin exposure, 4T score

No heparin exposure, 4T score = 0

Excluded

Autoimmune

ANA, Coombs, ESR

ANA negative, Coombs negative, ESR 18

Excluded

TTP/HUS

LDH, haptoglobin, schistocytes

LDH 160 IU/L, haptoglobin 52 mg/dL, no schistocytes

Excluded

Bone marrow

CBC, peripheral smear

Isolated thrombocytopenia, normal morphology

Excluded

HIV infection, Hep C, and Hep B

HIV Ag/Ab test, anti-HCV antibody, HBsAg, anti-HBc, and anti-HBs

Negative, negative, negative, negative, and positive

Excluded and vaccinated Hep B

Liver function test

AST, ALT, alkaline phosphatase, GGT, total bilirubin

34 U/L, 38 U/L, 56 U/L, 22U/L, 1.1 mg/dL

Normal test

Renal function and electrolytes

Creatinine, urea, Na, K, Cl, Mg, Ca

1.1 mg/dL, 22 mg/dL, 134 mmol/L, 3.7 mmol/L, 99 mmol/L, 1.9 mg/dL, 9.3 mg/dL

Borderline test

Vitamin B12 and folate

Serum values of vitamin B12 and folate

369 pmol/L, 14 ng/mL

Normal

RBC count

5.1 × 10⁶/µL

Normal