Raising Low Calcium Levels Helps Resolve Woman’s Heart Abnormalities

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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A woman in China developed rare changes in her heartbeat, which were associated with low blood calcium caused by hypoparathyroidism, according to a case report.

Using an electrocardiogram (ECG) — a line graph that shows how the electrical activity of the heart changes over time — scientists were able to detect certain abnormalities such as the so-called T-wave alternans. This is a beat-to-beat variation in the T-wave — a specific part of the graphed line — linked to a risk of developing changes in heart rhythm or sudden cardiac death.

“The etiology [cause] of T-wave alternans may easily be overlooked. It should thus be thoroughly investigated to avoid misdiagnosis and poor outcomes,” the scientists wrote.

The report, “Prolonged ST segment and T-wave alternans with torsade de pointes secondary to hypocalcemia due to hypoparathyroidism: A case report,” was published in Annals of Noninvasive Electrocardiology.

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Hypoparathyroidism is characterized by a deficiency of the parathyroid hormone (PTH), which helps the body control calcium, phosphorus, and vitamin D levels in the blood. People with hypoparathyroidism typically have hypocalcemia (low blood calcium).

Calcium keeps muscles and blood vessels working well and also helps control blood pressure. People with too low or too high levels of calcium in the blood are at risk of heart abnormalities.

A team of scientists reported the case of a 56-year-old woman who developed T-wave alternans and other changes in heartbeat, possibly due to hypocalcemia caused by hypoparathyroidism.

The woman was admitted to the hospital’s ophthalmology department for blurred vision in both eyes that had been getting worse over the previous three years.

“There was no obvious cause for the blurred vision, and there was no eye pain, redness, photophobia [light sensitivity], tearing, or difficulty opening the eyes,” the researchers wrote.

She also reported no nausea, vomiting, dizziness, or headache, and had no history of high blood pressure or other diseases. She had undergone a thyroidectomy — surgery to remove all or part of the thyroid gland — 11 years earlier due to the presence of an abnormal mass of tissue (neoplasm).

A physical exam showed no abnormalities in the heart, lungs, or abdomen. An eye exam revealed opacity of the lens and the clear gel (vitreous) that fills the eyeball.

An ECG revealed an irregularity indicating an abnormal heartbeat. A blood test revealed lower-than-normal calcium levels.

After being transferred to the cardiology department and given calcium supplementation, the patient was asked to wear a Holter monitor to record a continuous ECG over a certain amount of time. Using it, the researchers were able to detect both T-wave alternans and torsade de pointes, an abnormality indicated by a specific type of fast heart rhythm that begins in the two lower chambers of the heart.

The researchers also completed a thyroid function test that revealed a PTH deficiency. Based on this finding, the woman was diagnosed with hypoparathyroidism with hypocalcemia.

She was started on oral vitamin D and calcium supplements that raised blood calcium and PTH levels and led to resolving the heart abnormalities, including T-wave alternans.

“T-wave alternans is relatively low, and it is difficult to identify with the naked eye in clinical practice. This makes it prone to misdiagnosis and missed diagnosis, presenting a major challenge for ECG technicians and clinicians,” the scientists wrote.

“[T-wave alternans] is an important predictor of torsade de pointes; therefore, ECG technicians and clinicians must be able to identify its associated changes on ECG,” they said.