RESUMO
BACKGROUND: A previous nationwide study from Sweden showed that the rate of permanent hypoparathyroidism is high and under-rated in the Swedish Quality Register. This retrospective population-based study aimed to validate the rate and diagnosis of permanent hypoparathyroidism found in the previous study. A secondary aim was to assess the relationship between the rate of low parathyroid hormone (PTH) levels within 24â h after surgery and the rate of permanent hypoparathyroidism. METHODS: All patients who underwent total thyroidectomy from 2005 to 2015 in a region of Sweden were included. Data were retrieved from local health records, the National Patient Registry, the Swedish Prescribed Drug Registry, and the Swedish Quality Register. A strict definition of permanent hypoparathyroidism was used, including biochemical data and attempts to stop the treatment. RESULTS: A total of 1636 patients were included. Altogether, 143 patients (8.7 per cent) developed permanent hypoparathyroidism. Of these, 102 (6.2 per cent) had definitive permanent hypoparathyroidism, whereas 41 (2.5 per cent) had possible permanent hypoparathyroidism, because attempts to stop the treatment were lacking (28) or patients were lost to follow-up (13). The agreement between the Swedish Quality Register and the chart review was 29.3 per cent. A proportion of 23.2 per cent with a PTH level below the reference value corresponded to a 6.7 per cent rate of permanent hypoparathyroidism. CONCLUSION: The risk of permanent hypoparathyroidism after total thyroidectomy is high. Some patients are overtreated because attempts to stop the treatment are lacking. Quality registers might underestimate the risk of permanent hypoparathyroidism. Approximately one-quarter of all patients with low PTH levels immediately after surgery developed permanent hypoparathyroidism.
The parathyroid glands control calcium levels in the blood. If they do not make enough hormone, calcium levels are low. Parathyroid dysfunction can happen after thyroid surgery, if the glands are hurt or removed by mistake. This is a problem because people with this condition may have symptoms and need ongoing treatment with vitamin D and calcium. They might also face other health issues and need regular visits to their doctor. Finding out how often long-term parathyroid dysfunction happens can be tricky because it requires a full year of follow-up and attempts to stop the treatment. This information is often missing from many studies and registers. Some recent studies have shown that this condition is more common than previously thought. It would be helpful to have a quick way to know how common long-term parathyroid gland dysfunction will be within a unit or hospital, without having to wait for the follow-up. This would help doctors to assess how good they are at taking care of patients. It would also support research on new methods to avoid parathyroid dysfunction. The goal of the study was to see how often long-term parathyroid dysfunction occurs after thyroid surgery, using a strict definition and complete long-term follow-up. Another aim was to assess the link between low parathyroid hormone levels right after surgery and the rate of long-term parathyroid dysfunction. All individuals who had the entire thyroid gland removed for benign disease between 2005 and 2015 in a region of Sweden were included. Data were collected from local health records at six hospitals. Patient information, surgical details, blood tests, and treatment details were gathered from the medical charts. Data were also collected from the national quality register. A high rate of long-term parathyroid dysfunction was seen in this large study of 1636 patients, Some patients may have been overtreated, because no attempts had been made to stop the treatment. The rate of long-term parathyroid dysfunction in patients with a normal early parathyroid hormone level was very low. About 23 per cent of all patients had a low early parathyroid hormone level, which corresponded to a 6.7 per cent rate of long-term parathyroid dysfunction. The authors believe that parathyroid hormone measurement could help predict the rate of permanent hypoparathyroidism, but more studies are needed to be sure.