Table of Contents
- Key Points
- Background: The Medical Mystery
- Case Presentation: The Patient's Story
- Initial Examination and Test Results
- The Diagnostic Process
- Differential Diagnosis: What Else It Could Have Been
- Final Diagnosis and Confirming Tests
- Clinical Implications for Patients
- Limitations of This Case Study
- Recommendations for Patients
- Frequently Asked Questions
- Source Information
Key Points
- Vitamin B12 deficiency can cause severe anemia, low white blood cells, and low platelets.
- Extremely high LDH with low reticulocyte response is a key diagnostic pattern.
- Skin depigmentation (vitiligo) may indicate pernicious anemia as a cause.
- Symptoms can develop rapidly over weeks, contrary to traditional teaching.
Background: The Medical Mystery
This case from Massachusetts General Hospital demonstrates how vitamin deficiencies can sometimes present with dramatic and concerning symptoms that mimic more serious conditions. The patient's story highlights the importance of thorough diagnostic evaluation even when symptoms seem to point toward catastrophic illnesses.
Vitamin B12 deficiency affects approximately 6% of adults under 60 in the United States, with prevalence increasing with age. Despite being common, it can be overlooked when patients present with severe symptoms that suggest more acute medical emergencies.
Case Presentation: The Patient's Story
A 21-year-old man arrived at the hospital during summer months with concerning symptoms that had developed over four weeks. He had been completely healthy until experiencing nausea and vomiting that lasted one day, followed by persistent fatigue.
Two weeks before hospitalization, he developed additional symptoms including lightheadedness when changing positions and night sweats. His fatigue continued worsening until the morning of admission, when he experienced lightheadedness even while lying down, prompting his visit to the emergency department.
The patient worked as a carpenter with minimal outdoor exposure. He lived with family and had pets including two cats and a dog. He took no medications, didn't smoke or use alcohol or drugs, and had only one relevant family history detail—his maternal grandmother had lymphoma.
Initial Examination and Test Results
At the first hospital, doctors recorded vital signs showing a rapid heart rate of 121 beats per minute (normal is 60-100) and pale inner eyelids suggesting anemia. His initial blood tests revealed three critical abnormalities:
- Severe anemia: Hemoglobin of 5.1 g/dL (normal 14.0-18.0)
- Low white blood cells: 1,900 cells/μL (normal 4,800-10,800)
- Low platelets: 125,000 platelets/μL (normal 150,000-400,000)
Most strikingly, his lactate dehydrogenase (LDH)—a marker of cell damage—was extremely elevated at >2,500 U/L (normal 135-225). He received a blood transfusion and was transferred to Massachusetts General Hospital for specialized care.
At Mass General, his vital signs had improved with a heart rate of 89 beats per minute. Doctors noted areas of skin depigmentation (loss of color) near his elbows, fingers, and feet—a finding that would later prove important. His physical examination was otherwise normal.
The Diagnostic Process
Medical teams conducted extensive testing to determine the cause of his symptoms. His blood smear showed abnormal red blood cells including:
- Macroovalocytes (abnormally large oval-shaped red cells)
- Dacrocytes (teardrop-shaped cells)
- Neutrophils with increased segmentation (6 or more nuclear lobes)
- Some cells with basophilic stippling (abnormal blue speckling)
An abdominal ultrasound revealed mild spleen enlargement at 15.8 cm (normal <14.1 cm for his height and sex). Doctors performed numerous tests to rule out infections including Lyme disease, HIV, COVID-19, Epstein-Barr virus, cytomegalovirus, and parvovirus—all returned negative.
Differential Diagnosis: What Else It Could Have Been
The medical team considered multiple possible explanations for his severe symptoms:
Congenital diseases: Genetic conditions like GATA2 deficiency or Fanconi anemia were considered but deemed unlikely due to the rapid symptom onset (4 weeks versus years) and extremely high LDH level.
Infections: Various viral and bacterial infections were tested, but none typically cause such dramatically elevated LDH (nearly 3000 U/L) alongside macrocytic anemia.
Cancers: Leukemia or lymphoma were serious considerations given night sweats and family history, but preserved platelet and reticulocyte counts suggested bone marrow wasn't fully infiltrated by cancer cells.
Autoimmune disorders: Conditions like lupus or hemophagocytic lymphohistiocytosis were possible but lacked supporting evidence like fever or elevated ferritin.
Hemolytic anemia: The team ruled out conditions where the body destroys its own red cells because the reticulocyte response was too low given the degree of anemia and LDH elevation.
The diagnostic approach involved analyzing "scaling functions"—how different lab values related to each other in magnitude. The extremely high LDH (marker of cell damage) alongside relatively modest bilirubin elevation and low reticulocyte response created a pattern characteristic of vitamin B12 deficiency.
Final Diagnosis and Confirming Tests
The medical team ultimately diagnosed severe vitamin B12 deficiency. Confirmatory tests revealed:
- Vitamin B12 level: <150 pg/mL (severely deficient, normal >231 pg/mL)
- Methylmalonic acid: 1.00 nmol/mL (elevated, normal <0.40)
- Homocysteine: 21.5 μmol/L (elevated, normal 0-14.2)
- Folate level: 4.9 ng/mL (low normal, >4.7 considered adequate)
A bone marrow biopsy showed normocellularity with left-shifted erythroid hyperplasia—meaning his bone marrow was producing red blood cells that weren't maturing properly, characteristic of B12 deficiency.
The skin depigmentation noted earlier provided an important clue, as vitiligo (autoimmune skin depigmentation) is associated with pernicious anemia—an autoimmune condition that causes B12 deficiency.
Clinical Implications for Patients
This case demonstrates several important clinical insights about vitamin B12 deficiency:
Severe B12 deficiency can develop relatively quickly in some cases, contrary to the traditional teaching that depletion takes years. The hematologic (blood) and neurologic symptoms can occur independently—this patient had severe blood abnormalities without obvious nerve damage symptoms.
Laboratory patterns are crucial for diagnosis. The combination of extremely high LDH, modest bilirubin elevation, low reticulocyte response, and macrocytic anemia creates a distinctive pattern that experts can recognize.
Skin findings like vitiligo can provide diagnostic clues for associated autoimmune conditions that might cause B12 malabsorption.
Limitations of This Case Study
As a single case report, this presentation represents just one patient's experience. The rapid onset of severe symptoms might not be typical for most B12 deficiency cases.
The exact cause of this patient's B12 deficiency wasn't fully determined, though pernicious anemia (autoimmune condition) was suspected based on the vitiligo association. Not all patients will have such clear associated findings.
The dramatic lab abnormalities might lead to overtesting for more serious conditions before considering nutritional deficiencies, potentially delaying diagnosis in some cases.
Recommendations for Patients
If you experience persistent fatigue, lightheadedness, or night sweats:
- Seek medical evaluation rather than assuming symptoms are just from stress or lack of sleep
- Request basic blood tests including complete blood count (CBC) and possibly vitamin levels if deficiency is suspected
- Note any skin changes like depigmentation to discuss with your doctor
- Don't overlook nutritional causes even when symptoms seem severe—deficiencies can cause dramatic presentations
- Follow up on abnormal results even if you start feeling better, as underlying conditions need treatment
For patients with confirmed B12 deficiency, treatment typically involves B12 injections or high-dose oral supplements with regular monitoring to ensure levels normalize and symptoms resolve.
Frequently Asked Questions
What are the symptoms of severe vitamin B12 deficiency?
Severe vitamin B12 deficiency can cause fatigue, lightheadedness, night sweats, and pale skin. In this case, the patient also had nausea, vomiting, and skin depigmentation. Blood tests showed severe anemia, low white blood cells, low platelets, and extremely high LDH levels.
How is vitamin B12 deficiency diagnosed?
Diagnosis involves blood tests measuring vitamin B12, methylmalonic acid, and homocysteine levels. A complete blood count may show macrocytic anemia. In this case, a bone marrow biopsy revealed abnormal red blood cell production. The pattern of high LDH with low reticulocyte response is characteristic.
Can vitamin B12 deficiency be mistaken for leukemia?
Yes, because symptoms like fatigue, night sweats, and abnormal blood counts can mimic leukemia. However, in B12 deficiency, the reticulocyte count is low and LDH is extremely high, while bone marrow is not infiltrated by cancer cells. Proper testing distinguishes the conditions.
What blood test results indicate severe vitamin B12 deficiency?
Severe vitamin B12 deficiency is indicated by a vitamin B12 level below 150 pg/mL (normal >231 pg/mL), elevated methylmalonic acid above 0.40 nmol/mL, and elevated homocysteine above 14.2 μmol/L. Additionally, blood tests may show severe anemia, low white blood cell count, low platelet count, and a very high lactate dehydrogenase level.
Can vitamin B12 deficiency cause skin changes?
Yes, vitamin B12 deficiency can be associated with skin depigmentation, which is loss of skin color. In the case described, the patient had areas of depigmentation near his elbows, fingers, and feet. This finding is linked to vitiligo, an autoimmune condition that can cause pernicious anemia, a common cause of B12 deficiency.
How is vitamin B12 deficiency treated?
Treatment for confirmed vitamin B12 deficiency typically involves vitamin B12 injections or high-dose oral supplements. Regular monitoring is needed to ensure that vitamin B12 levels return to normal and symptoms resolve. The exact treatment plan should be determined by a healthcare provider based on the underlying cause and severity.
What are the long-term effects of untreated vitamin B12 deficiency?
Untreated vitamin B12 deficiency can lead to severe anemia, low white blood cell and platelet counts, and potentially neurological damage. In the case described, the patient had severe blood abnormalities but no obvious nerve damage. However, the article notes that hematologic and neurologic symptoms can occur independently, so untreated deficiency may cause nerve problems over time.
Source Information
Original Article Title: Case 6-2024: A 21-Year-Old Man with Fatigue and Night Sweats
Authors: Jonathan C.T. Carlson, M.D., Madeleine M. Sertic, M.B., B.Ch., and Maria Y. Chen, M.D., Ph.D.
Publication: The New England Journal of Medicine, February 22, 2024; 390:747-56
DOI: 10.1056/NEJMcpc2309498
This patient-friendly article is based on peer-reviewed research from Massachusetts General Hospital's Case Records.
