Acute Intermittent Porphyria mimicking Gitelman Syndrome presented with a transient tubulopathy in Pregnancy

The human body relies on a delicate balance of salts and fluids to keep nerves firing, muscles working, and the brain functioning clearly. When this balance tips too far in one direction, it can cause confusion, weakness, or even life-threatening crises. One rare genetic condition, known as acute intermittent porphyria, disrupts the body's ability to make a vital component of blood called heme. Usually, this disruption causes severe abdominal pain, vomiting, and nervous system problems. However, the condition is a master of disguise. It can hide behind other symptoms, making it difficult for doctors to recognize, especially when a patient is pregnant and the body is already undergoing massive natural changes. Understanding how this rare disorder presents in unexpected ways is crucial for preventing misdiagnosis and ensuring the safety of both mother and child.

In a recent report from Sri Lanka, doctors described a case where a young pregnant woman presented with a puzzle that defied standard medical expectations. At fourteen weeks into her pregnancy, she was referred for evaluation because her blood sodium levels remained dangerously low, even after her severe morning sickness had stopped. For months, she had suffered from hyperemesis gravidarum, a condition of extreme vomiting common in early pregnancy. By the time she reached eighteen weeks, the vomiting had ceased, yet her sodium level stayed at 122 millimoles per liter, far below the normal range. This persistence was the first clue that something more than simple dehydration was happening. Further tests revealed she was also losing potassium and magnesium through her kidneys, a pattern that initially led doctors to suspect a rare kidney disorder called Gitelman syndrome.

The medical team, working at the National Hospital of Sri Lanka, began a thorough investigation to find the root cause. They ruled out common hormonal issues and confirmed that her kidneys were functioning normally in terms of filtering waste. However, the urine tests showed a strange combination: high levels of sodium, potassium, and magnesium being wasted out of the body, despite the woman not being dehydrated. This specific mix of symptoms, where the body leaks essential salts, is not typical for the most common causes of low sodium. Because the patient had no history of abdominal pain, dark urine, or the severe nerve symptoms usually associated with porphyria, the doctors had to look deeper. They turned to advanced genetic testing, sequencing the entire set of her genes to see if a hidden mutation was at play.

The genetic search yielded a definitive answer. The team found a specific error in a gene called HMBS, which is responsible for making the enzyme that helps produce heme. This error, a single letter change in the genetic code, confirmed the diagnosis of acute intermittent porphyria. To make sense of this discovery, the doctors looked back at the family history. The patient revealed that her brother had died young after suffering from severe back pain and muscle wasting, and she herself had a history of unexplained abdominal pain and anxiety that seemed to flare up when she fasted. These past events, once dismissed as unrelated or psychological, suddenly fit the picture of a genetic disorder that had been lying dormant until the stress of pregnancy triggered it.

With the diagnosis confirmed, the medical team shifted their approach. They realized that the woman's body was reacting to the pregnancy by producing too many toxic byproducts of heme production, which were interfering with how her kidneys handled salts. Instead of treating her for a kidney disease, they focused on managing the porphyria. They ensured she ate a diet rich in carbohydrates to prevent fasting, which is a known trigger for attacks, and they carefully replaced the salts she was losing. Remarkably, she did not need any special, high-risk medications often used for acute porphyria attacks. She carried her pregnancy to term, delivering a healthy baby via a lower segment cesarean section at thirty-six weeks.

After the baby was born, the woman's body returned to its normal state on its own. Her sodium, potassium, and magnesium levels stabilized without the need for continued supplements. This outcome provided a clear link between the pregnancy, the genetic condition, and the strange electrolyte loss. The case serves as a powerful reminder that rare diseases can mimic common ones in unexpected ways. It suggests that when a pregnant woman has low sodium that does not improve after vomiting stops, doctors should consider checking for porphyria, even if the patient has no pain or classic neurological symptoms. By recognizing these subtle signs, medical teams can avoid long diagnostic journeys and provide the right care to keep both mother and baby safe.