Validating the risk of hypoparathyroidism after total thyroidectomy in a population-based cohort: plea for improved follow-up.

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 24 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.

Preoperative prophylactic active vitamin D to streamline total thyroidectomy.

BACKGROUND: Hypocalcaemia is a common complication after total thyroidectomy (TT). Treatment consists of calcium and active vitamin D supplementation. Low levels of vitamin D before surgery have been shown to be a risk factor for postoperative hypocalcaemia, yet studies examining routine preoperative vitamin D supplementation have shown conflicting results. This retrospective cohort study aims to investigate the potential benefit of preoperative active vitamin D supplementation on hypocalcaemia and its symptoms after TT. METHODS: This study included patients undergoing TT at Uppsala University Hospital from January 2013 to December 2020, resulting in a total of 401 patients after exclusion. Routine preoperative alfacalcidol treatment was initiated for all TT patients in January 2017 resulting in two groups for comparison: one group (pre-January 2017) that was prescribed preoperative alfacalcidol and one that was not. Propensity score matching was used to reduce bias. The primary outcome was early postoperative hypocalcaemia (serum calcium, S-Ca less than 2.10 mmol/l); secondary outcomes were symptoms of hypocalcaemia and length of stay. RESULTS: After propensity score matching, there were 108 patients in each group. There were 2 cases with postoperative day one S-Ca less than 2.10 in the treated group and 10 cases in the non-treated group (P < 0.001). No patients in the treated group had a S-Ca below 2.00 mmol/l. Preoperative alfacalcidol was associated with higher mean serum calcium level day one (2.33 versus 2.27, P = 0.022), and reduced duration of hospital stay (P < 0.001). There was also a trend toward fewer symptoms of hypocalcaemia (18.9 per cent versus 30.5 per cent, P = 0.099). CONCLUSIONS: Prophylactic preoperative alfacalcidol was associated with reduced biochemical hypocalcaemia and duration of hospital stay following TT. Also, with this protocol, it is suggested that routine day 1 postoperative S-Ca measurement is not required.

Risk of Permanent Hypoparathyroidism After Total Thyroidectomy for Benign Disease: A Nationwide Population-based Cohort Study From Sweden.

OBJECTIVE: To investigate the prevalence and risk factors for permanent hypoparathyroidism after total thyroidectomy for benign disease in a population-based setting with data independent of input of complication data. SUMMARY OF BACKGROUND DATA: The reported rate of permanent hypoparathyroidism is highly variable and mostly rely on reported complication data from national or institutional registries. METHODS: All patients who underwent total thyroidectomy in Sweden from 2005 to 2015 were identified through Scandinavian Quality Register for Thyroid, Parathyroid and Adrenal Surgery and the Swedish National Patient Register. Patients were matched to outcome data from the Swedish Prescribed Drug Register. Permanent hypoparathyroidism was defined as treatment with calcium and/or active vitamin D more than 1 year after surgery. RESULTS: Seven thousand eight hundred fifty-two patients were included and 938 (12.5%) developed permanent hypoparathyroidism. The risk was lower in patients registered in the quality register (11.0% vs 16%, P < 0.001). In a multivariable analysis there was a higher risk of permanent hypoparathyroidism in patients with parathyroid autotransplantation [Odds ratio (OR) 1.72; 95% confidence interval 1.47-2.01], center-volume <100 thyroidectomies per year (OR 1.22; 1.03-1.44), age above 60 year (OR 1.64; 1.36-1.98) and female sex (OR 1.27; 1.05-1.54). Reported data from the quality register only identified 178 of all 938 patients with permanent hypoparathyroidism. CONCLUSION: The risk of permanent hypoparathyroidism after total thyroidectomy was high and associated with parathyroid autotransplantation, higher age, female sex and surgery at a low volume center. Reported follow-up data might underestimate the rate of permanent hypoparathyroidism.