Severe COVID-19 Suspected as Cause of Temporary Hypoparathyroidism

Marta Figueiredo, PhD avatar

by Marta Figueiredo, PhD |

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Severe COVID-19 could lead to the development of temporary hypoparathyroidism, a case report suggests.

This report represents the third case of hypoparathyroidism secondary to severe COVID-19 infection noted in scientific literature.

These rare instances, along with previous reports showing that the virus may worsen previously well-controlled hypoparathyroidism, highlight the damaging effects that COVID-19 can have on the parathyroid glands.

The case study, “COVID-19 induced hypoparathyroidism: A case report,” was published in the journal Experimental and Therapeutic Medicine.

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Hypoparathyroidism is characterized by abnormally low levels of the parathyroid hormone (PTH), which is produced by the parathyroid glands, located in the neck region. PTH deficiency results in low levels of calcium and high levels of phosphorus in the blood, as well as a deficiency in vitamin D, which helps the body absorb calcium.

Hypoparathyroidism is mostly associated with accidental injury to the parathyroid glands during neck surgery, but autoimmune conditions, genetic mutations, cancer, radiation, and other diseases may also cause the condition.

COVID-19 infection, caused by the SARS-CoV-2 virus, affects several organs, most often the lungs. The virus can also cause damage to hormone-producing glands, either directly by its entry and multiplication, or indirectly by promoting blood vessel inflammation, blood clots, and excessive immune responses.

SARS-CoV-2’s entry into cells is dependent on the presence of a cell surface receptor protein called ACE2. While ACE2 levels are highest in the lungs and intestinal absorptive cells, elevated levels have also been reported in specific parathyroid gland cells.

Low blood calcium levels, or hypocalcemia, are also commonly reported in people with COVID-19, and they have been suggested as an important indicator of COVID-19 severity. However, these findings appear to be mainly linked to vitamin D deficiency.

While evidence suggests that COVID-19 may also affect the parathyroid glands, this has “received limited attention,” the researchers wrote. Only two previous cases of hypoparathyroidism secondary to severe SARS-CoV-2 infection have been reported in the literature.

A team of researchers in Greece described what is most likely the third case of such a link.

A 53-year-old man came to Laiko General Hospital, in Athens, complaining of fever and cough for the past 10 days. He did not smoke, was not on any medication, and had a successful surgery for colon cancer 10 years earlier, with no evidence of the cancer’s return.

Examination confirmed the fever and showed lower-than-usual blood-oxygen levels. Excessive fluid in the airways of both lower lungs was suspected and later confirmed by X-ray.

Blood work showed high levels of C-reactive protein and ferritin — two markers of inflammation — low counts of white blood cells and platelets, hypocalcemia, and higher-than-normal phosphorus levels.

A nasal swab confirmed COVID-19 in the man, who had not been vaccinated against SARS-CoV-2. He was transferred to the hospital’s COVID-19 unit and given oxygen therapy, as well as immunosuppressive, anti-viral, and anti-blood clotting treatment.

A CT scan of the patient’s chest revealed alterations consistent with COVID-19 pneumonia.

Given that his low calcium and high phosphorus blood levels suggested hypoparathyroidism, further blood tests were done. These showed the man also had PTH deficiency, but normal vitamin D levels, and confirmed the diagnosis of hypoparathyroidism.

Clinical records showed that his blood calcium levels were within normal range six months earlier, and he had no history of neck surgery, trauma, regional radiation, or other diseases known to potentially cause hypoparathyroidism. Further testing also ruled out autoimmune disease and cancer.

Therefore, hypoparathyroidism “was considered to have been caused by SARS-CoV-2 infection,” the researchers wrote.

The man received oral calcium supplements for hypoparathyroidism. After five days of hospitalization, his clinical condition and blood calcium levels had improved. The levels of both calcium and phosphorus returned to normal one month after his discharge, indicating the resolution of hypoparathyroidism.

This case “highlighted the effect of the novel coronavirus on parathyroid glands,” the researchers wrote.

They also noted that at least three reported cases of temporary hypoparathyroidism decompensation, or functional deterioration, due to COVID-19. In all three cases, previously well-controlled or sub-clinical hypoparathyroidism worsened upon SARS-CoV-2 infection.

As such, “clinicians should also keep in mind that, despite the fact that SARS-CoV-2 has no known specific orientation toward the parathyroid glands, it can result in primary hypoparathyroidism and decompensation of old primary hypoparathyroidism,” the researchers concluded.