A 15-month-old child became seriously ill because of severe vitamin D deficiency, which caused their heart to become enlarged and weak—a condition called dilated cardiomyopathy. This is a rare but dangerous complication that doctors don’t always think about. The good news is that when doctors gave the child vitamin D supplements, their heart recovered completely within a few months. This case shows that doctors need to check for vitamin D deficiency in young children, especially those who are only breastfed, because catching it early can prevent life-threatening heart problems.

The Quick Take

  • What they studied: Whether severe vitamin D deficiency can cause a child’s heart to become dangerously enlarged and weak
  • Who participated: One 15-month-old child who was exclusively breastfed and developed serious heart problems
  • Key finding: A toddler’s severely enlarged and weakened heart returned to normal size and function within 19 months after receiving vitamin D supplements
  • What it means for you: If you have a breastfed baby, talk to your doctor about vitamin D supplementation. Vitamin D deficiency is preventable, and catching it early can stop serious heart problems before they start. This is especially important if your baby seems unusually tired or has trouble breathing.

The Research Details

This is a case report, which means doctors documented the story of one specific patient to teach others about an unusual medical situation. The doctors described how a 15-month-old child came to the hospital very sick with heart failure, what tests they ran, and how the child recovered after treatment. Case reports are like medical detective stories—they help doctors recognize patterns they might otherwise miss. In this case, the doctors noticed that the child’s vitamin D levels were dangerously low and that treating this deficiency fixed the heart problem. While case reports only describe one person’s experience, they can be important for alerting doctors to watch for rare but serious complications.

Case reports are valuable because they can identify rare complications that might not show up in larger studies. This report is important because it reminds doctors that vitamin D deficiency—which is common in breastfed babies—can sometimes cause severe heart damage. By sharing this case, the doctors help other healthcare providers recognize similar situations early and prevent tragedy.

This is a single case report, so it shows what happened to one child but cannot prove that vitamin D deficiency always causes heart problems. However, the doctors provided detailed medical records, blood tests, and heart imaging (echocardiography) that clearly showed the problem and recovery. The fact that the child’s heart normalized after vitamin D treatment strongly suggests the vitamin D deficiency was the cause. Readers should understand this describes a rare outcome, not something that happens to most vitamin D-deficient children.

What the Results Show

The 15-month-old child arrived at the hospital in cardiogenic shock, which means their heart was so weak it couldn’t pump enough blood to keep their body working properly. Blood tests showed the child had severe vitamin D deficiency. Heart imaging showed the child’s heart was enlarged and not pumping effectively—a condition called dilated cardiomyopathy. After the doctors started vitamin D supplements, the child’s blood chemistry improved within one week. Most importantly, follow-up heart imaging at 19 months showed the child’s heart had returned to normal size and function. This dramatic recovery suggests the vitamin D deficiency was directly causing the heart damage.

The child’s metabolic parameters (the chemical balance in their blood) normalized quickly—within just one week of starting vitamin D treatment. This rapid improvement in blood chemistry likely helped the heart begin healing. The complete recovery of heart function by 19 months shows that even severe vitamin D-related heart damage can be reversible if caught and treated.

Vitamin D deficiency is known to cause rickets (weak bones) in children, especially those who are exclusively breastfed. However, severe heart damage from vitamin D deficiency is rare and not commonly discussed. This case adds to a small body of medical literature showing that vitamin D deficiency can occasionally cause serious heart complications. It emphasizes that doctors should think about vitamin D deficiency when they see unexplained heart problems in young children.

This report describes only one child, so we cannot say how often vitamin D deficiency causes heart problems. We don’t know if other factors might have contributed to this child’s heart damage. The case doesn’t tell us how many breastfed babies with vitamin D deficiency develop heart problems versus how many stay healthy. Doctors need larger studies to understand exactly how common this complication is and which children are at highest risk.

The Bottom Line

Parents of exclusively breastfed infants should discuss vitamin D supplementation with their pediatrician. The American Academy of Pediatrics recommends vitamin D drops for breastfed babies starting in the first few days of life. This is a straightforward, safe, and inexpensive way to prevent deficiency. If your child shows signs of unusual tiredness, poor feeding, or difficulty breathing, seek medical attention promptly. Confidence level: High—vitamin D supplementation is well-established as safe and effective prevention.

Parents of breastfed babies should care most about this finding, since breastfed infants are at higher risk for vitamin D deficiency than formula-fed babies. Pediatricians should be aware that severe vitamin D deficiency can occasionally cause heart problems, not just bone problems. Healthcare providers working with at-risk populations (low sunlight exposure, dietary restrictions, or exclusively breastfed infants) should maintain awareness of this rare complication. People who are not breastfeeding or who already supplement with vitamin D have lower risk.

Vitamin D supplementation should begin in the first days of life as prevention. If deficiency develops, blood chemistry can improve within one week of treatment. However, heart recovery takes much longer—in this case, 19 months for complete normalization. Early detection and treatment offer the best chance for full recovery.

Want to Apply This Research?

  • Track your breastfed baby’s vitamin D supplementation daily (yes/no), noting the dose and date. Also monitor for warning signs like unusual fatigue, poor feeding, or rapid/difficult breathing, and log any concerning symptoms to discuss with your pediatrician.
  • Set a daily reminder to give your breastfed baby their vitamin D drops at the same time each day (for example, with the first feeding). Make it part of your morning routine so you don’t forget. If you’re unsure about the right dose, use the app to store your pediatrician’s recommendation.
  • Use the app to track supplementation consistency over months and years. Set quarterly reminders to review your child’s vitamin D status with your pediatrician through routine blood work. Log any health concerns or changes in energy levels to identify patterns and share with your healthcare provider.

This case report describes a rare but serious complication of vitamin D deficiency. It is not medical advice. If you are breastfeeding, consult your pediatrician about appropriate vitamin D supplementation for your infant—this is standard preventive care. If your child shows signs of heart problems (unusual tiredness, difficulty breathing, poor feeding, or bluish skin color), seek emergency medical care immediately. This article is for educational purposes and should not replace professional medical evaluation and treatment.