A 33-year-old woman was found to have two rare diseases at the same time: VLCAD deficiency (a metabolic disorder affecting fat breakdown) and Hashimoto’s thyroiditis (an autoimmune thyroid disease). This appears to be the first documented case of both conditions occurring together, suggesting that mitochondrial dysfunction may trigger chronic inflammation and autoimmune disease. The patient improved significantly with treatment including a special diet, supplements, and thyroid medication.
Doctors discovered something unusual: a 33-year-old woman had two separate rare conditions happening at the same time. One affected how her body breaks down fats for energy (VLCAD deficiency), and the other was an autoimmune disease attacking her thyroid (Hashimoto’s thyroiditis). This case report suggests these two conditions might be connected through inflammation in the body. According to Gram Research analysis, the patient improved significantly with treatment including special diet, supplements, and thyroid medication. While this is just one patient’s story, it opens new questions about whether mitochondrial problems—issues with the energy-producing parts of cells—might trigger autoimmune diseases.
Key Statistics
A 2026 case report published in BMC Endocrine Disorders documented the first known coexistence of VLCAD deficiency and Hashimoto’s thyroiditis in a 33-year-old woman, suggesting a potential mechanistic link between mitochondrial dysfunction and autoimmune thyroid disease.
The patient presented with severe rhabdomyolysis (muscle breakdown) and elevated anti-TPO and anti-Tg antibodies indicating autoimmune thyroiditis, with genetic testing confirming a homozygous ACADVL mutation (c.1097G>A) characteristic of VLCAD deficiency.
Following treatment with intravenous hydration, L-carnitine supplementation, a medium-chain triglyceride-enriched diet, and levothyroxine, the patient showed marked improvement and remained stable without recurrence for one year.
The Quick Take
- What they studied: Whether two rare diseases—a metabolic disorder affecting fat breakdown and an autoimmune thyroid disease—could occur together in one person and share a common cause
- Who participated: One 33-year-old woman who experienced muscle pain, fatigue, and dark urine, with a history of unexplained muscle breakdown episodes
- Key finding: Genetic testing revealed the patient had VLCAD deficiency (a rare fat-metabolism disorder), and thyroid tests showed Hashimoto’s thyroiditis. This appears to be the first documented case of both conditions occurring together in one person.
- What it means for you: If you have unexplained muscle problems or thyroid disease, doctors may need to look deeper for underlying metabolic issues. This case suggests that sometimes multiple rare conditions can occur together, so comprehensive testing may be important.
The Research Details
This is a case report—a detailed medical story about one patient. A 33-year-old woman came to the hospital with severe muscle pain, extreme tiredness, and dark urine. Doctors ran blood tests and found her muscles were breaking down (rhabdomyolysis). They also discovered her thyroid wasn’t working properly and that her immune system was attacking her thyroid cells. Because she had a history of unexplained muscle breakdown, doctors performed genetic testing to find the root cause. The genetic test revealed a specific mutation in the ACADVL gene, confirming VLCAD deficiency—a rare condition where the body can’t properly break down long-chain fatty acids for energy.
Case reports are important because they describe unusual or never-before-seen combinations of diseases. This helps doctors recognize patterns they might otherwise miss. By documenting this patient’s story, doctors can alert other physicians to watch for similar combinations and may help other patients get diagnosed faster.
This is a single-patient case report, which is the lowest level of research evidence. However, it’s valuable because it documents something that appears to have never been reported before. The diagnosis was confirmed with genetic testing, which is very reliable. The patient was followed for one year, showing the treatment worked. Readers should understand this describes one person’s experience and cannot prove that these two conditions are always connected.
What the Results Show
The patient presented with acute severe muscle breakdown (rhabdomyolysis) with dark-colored urine, a sign that muscle proteins were being released into the bloodstream. Blood tests confirmed severe muscle damage. Thyroid testing showed the patient had primary hypothyroidism (underactive thyroid) with elevated antibodies against thyroid peroxidase (anti-TPO) and thyroglobulin (anti-Tg), indicating autoimmune thyroid disease. Ultrasound imaging of the thyroid confirmed chronic autoimmune thyroiditis (Hashimoto’s disease). Genetic testing identified a homozygous mutation (c.1097G>A) in the ACADVL gene, confirming VLCAD deficiency. This genetic finding was the key to understanding why the patient had recurrent unexplained muscle breakdown episodes throughout her life.
The patient had a significant medical history of recurrent muscle breakdown episodes without any obvious external cause (like exercise or trauma). This pattern suggested an underlying metabolic problem rather than a one-time injury. The combination of metabolic dysfunction and autoimmune disease in one person suggests a potential link between how cells produce energy and how the immune system functions.
According to research reviewed by Gram, VLCAD deficiency and Hashimoto’s thyroiditis have never been documented together in the medical literature before. Both are rare conditions individually. VLCAD deficiency affects approximately 1 in 40,000 to 120,000 people, while Hashimoto’s thyroiditis is more common but still represents the leading cause of hypothyroidism in iodine-sufficient areas. The novelty of this case suggests doctors should be alert to potential connections between metabolic and autoimmune diseases.
This is a single case report involving one patient, so the findings cannot be generalized to all people with these conditions. We cannot prove that VLCAD deficiency causes Hashimoto’s thyroiditis or vice versa—this case simply shows they can occur together. The patient received multiple treatments simultaneously (hydration, supplements, diet changes, and thyroid medication), so we cannot determine which treatment was most important. Longer follow-up and studies of more patients would be needed to confirm whether this association is coincidental or causal.
The Bottom Line
If you have unexplained muscle breakdown episodes or muscle pain combined with thyroid problems, ask your doctor about comprehensive metabolic testing. If you have VLCAD deficiency, thyroid function should be monitored. If you have Hashimoto’s thyroiditis with unusual muscle symptoms, metabolic screening may be warranted. These recommendations are based on a single case, so discuss with your healthcare provider whether they apply to your situation. (Confidence level: Low, based on single case report)
People with unexplained muscle breakdown, people with VLCAD deficiency, people with Hashimoto’s thyroiditis, and healthcare providers caring for patients with rare metabolic or autoimmune diseases. This case is particularly relevant for doctors who see patients with multiple rare conditions that don’t seem to have an obvious connection.
In this case, the patient showed marked improvement within days to weeks of starting treatment (intravenous hydration, L-carnitine, special diet, and thyroid medication) and remained stable for at least one year. However, individual responses to treatment vary, and this timeline reflects one patient’s experience.
Frequently Asked Questions
Can you have two rare genetic diseases at the same time?
Yes, though it’s uncommon. This case report documents a woman with both VLCAD deficiency and Hashimoto’s thyroiditis occurring together. While both are individually rare, their coexistence suggests doctors should consider comprehensive testing when patients have multiple unexplained symptoms.
What causes VLCAD deficiency and how is it treated?
VLCAD deficiency is caused by mutations in the ACADVL gene, preventing the body from breaking down long-chain fatty acids for energy. Treatment includes a special diet rich in medium-chain triglycerides (MCTs), L-carnitine supplementation, and avoiding prolonged fasting or strenuous exercise without proper fueling.
Is there a connection between metabolic disorders and autoimmune thyroid disease?
This case suggests a potential link through chronic inflammation and mitochondrial dysfunction, but more research is needed. The patient’s mitochondrial problems may have triggered systemic inflammation that activated the immune system against the thyroid, though this remains speculative based on one case.
What should I do if I have unexplained muscle pain and thyroid problems?
Discuss comprehensive testing with your doctor, including thyroid antibody tests and potentially metabolic screening. While this combination is rare, thorough evaluation can help identify underlying conditions. Don’t assume symptoms are unrelated—sometimes multiple rare conditions occur together.
How long does it take to see improvement with VLCAD treatment?
In this case, the patient showed marked improvement within days to weeks of starting treatment. However, individual responses vary. Consistent adherence to diet, supplements, and medical management is important for long-term stability and preventing muscle breakdown episodes.
Want to Apply This Research?
- Track muscle pain episodes (frequency, severity, duration) and energy levels daily using a 1-10 scale. Note any dark urine or unusual fatigue. Record thyroid medication adherence and any symptoms of hypothyroidism (cold sensitivity, weight changes, fatigue).
- If diagnosed with VLCAD deficiency, use the app to monitor adherence to a medium-chain triglyceride (MCT) diet and L-carnitine supplementation. Set reminders for thyroid medication if you have Hashimoto’s. Log any muscle pain or fatigue patterns to share with your doctor.
- Create a monthly summary view showing muscle symptom trends, energy levels, and medication adherence. Share this data with your healthcare provider during check-ups to help them assess treatment effectiveness and adjust care as needed.
This article describes a single case report of one patient and should not be used for self-diagnosis. VLCAD deficiency and Hashimoto’s thyroiditis are serious medical conditions requiring professional diagnosis and treatment. If you experience unexplained muscle pain, dark urine, severe fatigue, or thyroid symptoms, consult a healthcare provider immediately. The coexistence of these conditions is extremely rare, and this case report does not establish that one condition causes the other. Always work with qualified medical professionals for diagnosis, testing, and treatment decisions. This content is for educational purposes only and is not a substitute for professional medical advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.