A new case study describes a woman who developed severe low phosphate levels after receiving iron infusions to treat anemia. Iron infusions, while usually safe, can sometimes cause the body to lose too much phosphate through the kidneys. This woman’s condition was made worse because she also had celiac disease, which prevented her body from absorbing nutrients properly. She needed weeks of special intravenous treatment to recover. This case helps doctors recognize and treat this rare but serious side effect, especially in patients with digestive problems.
The Quick Take
- What they studied: What happens when iron infusions cause dangerously low phosphate levels, and how to recognize and treat this problem
- Who participated: One 40-year-old woman with newly diagnosed celiac disease and severe iron deficiency anemia who received iron infusions
- Key finding: The patient developed severe low phosphate levels (0.34 mmol/l, much lower than normal) within one week of receiving iron infusions, requiring 5.5 weeks of continuous intravenous phosphate treatment to recover
- What it means for you: If you receive iron infusions, especially if you have digestive problems like celiac disease, doctors should monitor your phosphate levels. This is a rare but serious side effect that requires prompt medical attention and specialized treatment
The Research Details
This is a case report, which means doctors documented what happened to one patient in detail. A 40-year-old woman with celiac disease received two iron infusions (a total of 1.5 grams) to treat severe anemia. Within one week, she developed severe low phosphate levels and experienced fatigue, shortness of breath, and joint pain. Doctors ran blood tests and found that her kidneys were losing too much phosphate. This pattern of problems is called ‘6H syndrome,’ which describes six related mineral and hormone imbalances that can occur together.
The patient’s celiac disease made the situation worse because her damaged intestines couldn’t absorb nutrients properly, including phosphate from food. Regular phosphate supplements taken by mouth didn’t work because her intestines couldn’t absorb them. She needed continuous intravenous phosphate infusions (delivered directly into her bloodstream through a special catheter) for 5.5 weeks, along with vitamin D treatment and careful diet management.
The doctors tracked her recovery carefully and found that her phosphate levels gradually improved over 8.5 weeks total, with her symptoms resolving as her phosphate levels normalized.
This detailed case study is important because it shows doctors a clear pattern of what can go wrong after iron infusions. By documenting this severe case, the researchers help other doctors recognize similar problems earlier in their own patients. The case also highlights how having another condition like celiac disease can make iron infusion side effects much worse, which is crucial information for doctors treating patients with multiple health problems.
This is a single case report, which means it describes one patient’s experience in detail rather than comparing many patients. Case reports are useful for identifying rare side effects and teaching doctors about unusual presentations, but they cannot prove that something happens to everyone. The strength of this report is the thorough documentation of the patient’s blood tests, symptoms, and treatment response over time. However, because it’s only one patient, we cannot know how common this severe reaction is or whether it would happen the same way in other people.
What the Results Show
The main finding is that iron infusions can cause severe, prolonged low phosphate levels that are difficult to treat with standard methods. In this case, the patient’s phosphate dropped to 0.34 mmol/l (normal is around 0.8-1.4 mmol/l), which is dangerously low. Her kidneys were losing about 109.4 mmol of phosphate per day in her urine—far more than normal.
The patient experienced significant symptoms from this low phosphate, including severe fatigue, shortness of breath during physical activity, and joint pain. These symptoms gradually improved as her phosphate levels were restored through intravenous treatment.
The doctors identified that the iron infusion triggered a cascade of mineral imbalances affecting phosphate, calcium, vitamin D, and parathyroid hormone levels—a pattern they call ‘6H syndrome.’ This framework helps doctors understand that when one mineral goes wrong after an iron infusion, they should check for related problems in other minerals and hormones.
Recovery took longer than typical cases of low phosphate, requiring 5.5 weeks of continuous intravenous phosphate infusions plus vitamin D treatment. By 8.5 weeks after the problem started, her phosphate levels stabilized at 0.9 mmol/l and her symptoms resolved.
The case revealed that the patient’s celiac disease significantly worsened her condition. Because her intestines were damaged from celiac disease, she couldn’t absorb phosphate from food or oral supplements, making the kidney losses even more problematic. Her secondary hyperparathyroidism (overactive parathyroid glands responding to low calcium) was another important finding that required treatment with activated vitamin D (calcitriol). The combination of iron infusion effects plus malabsorption from celiac disease created a complex medical situation that required specialized care.
The researchers note that while iron infusions are increasingly recognized to cause low phosphate levels, most cases are mild and temporary. This case represents a severe and prolonged version of a known side effect. The ‘6H syndrome’ framework they describe helps organize understanding of how iron infusions disrupt multiple related mineral systems. Previous research has shown that iron infusions can trigger the body’s production of a hormone called fibroblast growth factor-23, which causes kidneys to waste phosphate. This case demonstrates that in patients with additional malabsorption problems, this effect can become severe and treatment-resistant.
This is a single case report, so we cannot know how often this severe reaction occurs or whether it would happen the same way in other patients. The patient had celiac disease, which is not typical for all patients receiving iron infusions, so her experience may not apply to everyone. We don’t know if other patients with celiac disease would have the same severe reaction, or if patients without celiac disease might also develop this problem. The case doesn’t compare different treatment approaches, so we can’t say whether other treatments might work better or faster. Finally, because this is one patient’s story, we cannot calculate statistics about risk or predict who is most likely to develop this complication.
The Bottom Line
Doctors should monitor phosphate levels in patients receiving iron infusions, especially those with digestive disorders like celiac disease (moderate confidence based on this case). Patients should report symptoms like unusual fatigue, shortness of breath, or joint pain after iron infusions to their doctors promptly (moderate confidence). Doctors should consider checking for the full pattern of ‘6H syndrome’ when low phosphate is detected after iron infusions, rather than treating it in isolation (moderate confidence). Patients with known malabsorption disorders may need more intensive monitoring and earlier specialist involvement (moderate confidence based on this case).
This information is most relevant for people with celiac disease or other digestive disorders who need iron infusions. It’s also important for doctors treating patients with these conditions. People receiving iron infusions for anemia should be aware of this rare but serious possibility. However, it’s important to remember that this is a rare complication—most people tolerate iron infusions well. This case should not discourage people from getting necessary iron treatment, but rather encourage careful monitoring.
In this case, severe symptoms developed within one week of the iron infusion. Recovery took 8.5 weeks total, with the most intensive treatment (continuous intravenous phosphate) needed for 5.5 weeks. However, this represents a severe case. Milder cases of low phosphate after iron infusions typically resolve faster. If you receive an iron infusion, watch for symptoms over the following weeks and report any concerns to your doctor immediately.
Want to Apply This Research?
- If you receive iron infusions and have a digestive disorder, track your energy levels daily (rate 1-10), note any shortness of breath during normal activities, and record any joint or muscle pain. Log these symptoms weekly in your health app to share with your doctor.
- After receiving an iron infusion, schedule a follow-up blood test with your doctor within 1-2 weeks to check phosphate levels, especially if you have celiac disease or other digestive conditions. Set phone reminders to report any new symptoms of unusual fatigue or shortness of breath to your healthcare provider immediately rather than waiting for a scheduled appointment.
- Create a long-term tracking system that records phosphate levels (if available from blood tests), energy levels, and any symptoms for at least 8-12 weeks after iron infusions. Share this data with your doctor to help identify patterns and catch problems early. If you have celiac disease, maintain this tracking even after symptoms resolve, as the case shows that problems can persist for weeks.
This case report describes one patient’s experience with a rare but serious side effect of iron infusions. It is not medical advice and should not replace consultation with your healthcare provider. If you have celiac disease or other digestive disorders and are considering or receiving iron infusions, discuss this case with your doctor to determine if additional monitoring is appropriate for your situation. If you experience unusual fatigue, shortness of breath, or joint pain after an iron infusion, contact your healthcare provider promptly. Do not stop or change any prescribed treatments without medical guidance.