07 May 2025
: Case report 
A Rare Case of Hypoxia and Cyanosis Secondary to Multifactorial Medication-Induced Sulfhemoglobinemia
Challenging differential diagnosis, Unusual or unexpected effect of treatment, Rare disease, Adverse events of drug therapy, Clinical situation which can not be reproduced for ethical reasons
Megan M. Mansour BE 1, Robert M. Seby BE 1, Aya Elalfy BDEF 1, Mario El Hayek BCDE 2, Tuhama S. Rihani CDE 3,4, Edson J. Mwakyanjala CDE 3,4, Libardo Rueda Prada
ABCDEFG 3,4*
DOI: 10.12659/AJCR.947587
Am J Case Rep 2025; 26:e947587
Table 1 Summary of laboratory workup, pulse oximetry, and oxygen requirements during hospital stay. Dark orange font highlights saturation gap present.
| Parameter (normal values) | Time of presentation | Time of admission | First 6 hours | Day 2 | Day 4 | Day 5 | Day 7 (discharge day) |
|---|---|---|---|---|---|---|---|
| Pulse oximetry (%) | 83 | 91 | 97 | 98 | |||
| FiO2 (%) | 21 | 44 | 100 | 100 | 100 | 40 | 21 |
| ABG with co-oximetry, oxygen saturation (94–98%) | – | – | – | 94.4 | |||
| PaO2 (83–108 mmHg) | – | – | 242.6 | 554.6 | 269.3 | 138 | 120.6 |
| ABG, MetHb (<1.5%) | – | – | “?” | “?” | 0 | 0 | 0 |
| Hemoglobin (11.6–15.0 g/dL) | – | 9.9 | 8.5 | 8.3 | 8 | 7.3 | 8.2 |
| Total bilirubin (0.0–1.2 mg/dL) | – | – | 3.2 | 1.5 | 1.7 | 1.3 | – |
| Direct bilirubin (0.0–0.3 mg/dL) | – | – | 1 | 0.6 | 0.5 | 0.5 | – |
| LDH (122–222 U/L) | – | – | 204 | 280 | 282 | 253 | – |
| Peripheral blood smear with few schistocytes. Haptoglobin <14 mg/dL (30–200 mg/dL). Iron 87 mcg/dL (35–145 mcg/dL). TIBC 144 mcg/dL (250–400 mcg/dL). TSAT 60% (14–50%). Folate level >20 mcg/L (≥4 mcg/L). Vitamin B12 555 ng/L (180–914 ng/L). Absolute reticulocyte count 243.2×10/L (30.4–110.9×10/L). G6PD enzyme activity 9.7 U/g Hb (8.0–11.9 U/g Hb). Direct coombs: Negative | |||||||
| Serum methemoglobin 0.8% (0.0–1.5%). Serum sulfhemoglobin 1.3% (0.0–0.4%) | |||||||
| Hemoglobin electrophoresis: Alpha-1 globin sequencing: Negative. Alpha-2 globin sequencing: Negative. Beta globin sequencing: Negative. DNA sequence analysis of the alpha and beta globin genes did not identify a mutation associated with a hemoglobinopathy or thalassemia | |||||||
| Fraction of inspired oxygen (FiO2). Arterial blood gas (ABG). Partial pressure of oxygen (PaO2). Methemoglobin (MetHb). Lactate dehydrogenase (LDH). Total iron-binding capacity (TIBC). Transferrin saturation (TSAT). Glucose-6-phosphate dehydrogenase (G6PD). “?” refers to the methemoglobin level result obtained in ABG with co-oximetry. | |||||||