This is a retrospective cohort study conducted at KS Hegde Medical Academy, Mangalore, India, from January 2019 to December 2019. Study was done on all PH patients attending endocrinology Outpatients Department during last 10 years. The informed patient consent was waived by obtaining approval from Institutional/National Review Board Committee due to the retrospective nature of study (EC/NEW/INST/2020/834).

Inclusion criteria: All patients irrespective of age and duration of disease were included in the study. All patients who were regular in follow-up for at least three years.

Exclusion criteria: Patients with irregular follow-up with insufficient clinical and biochemical data were excluded.

The data was collected regarding their original diagnosis prior to surgery, type of thyroid surgery, hypocalcaemic symptoms, hypercalcaemic symptoms, ureteric colic, ultrasonographic findings, dose of calcium and calcitriol.

Patients are diagnosed to have PH when their intact PTH concentration was less than 13 pg/mL in presence of hypocalcaemia and requirement of replacement with calcium with or without calcitriol for more than one year after surgery [9].

Hypocalcaemia was defined as a serum calcium less than 8.5 mg/dL in presence of normal albumin levels and or presence of carpopedal spasm and paraesthesias. When serum calcium is more than 10.5 mg/dL with normal serum albumin, patient is diagnosed as having hypercalcaemia. Renal failure was diagnosed, whenever creatinine value raised above 1.4 mg/dL and/ or an estimated GFR less than 60 mL/min/1.73 m² [5].

Statistical analysis was conducted using SPSS version 19. Mean and standard deviation was calculated. Categorical variables were presented as percentage while mean and standard deviation were used to document quantitative variables.

In this study, a total of 23 patients were included, out of which 20 patients were females and three males. Their mean age of presentation was 41.2±15.2 years. Majority of patients had malignant disease (18 patients). In these 18 patients, 14 had thyroid malignancy and four had laryngeal malignancy. In all these patients total thyroidectomy was done along with laryngectomy in four patients with laryngial malignancy. The remaining five patients had benign disease i.e., large multi nodular goitre in three patients and resistant graves’ disease with huge goitre in two patients. Out of these patients, two patients underwent total thyroidectomy and three patients had near total thyroidectomy. Thirteen patients underwent total thyroidectomy with lymphnode dissection due to suspicion of underlying malignancy. Demographic data of 23 patients with postoperative Permanent Hypoparathyroidism (PH) has been represented in [Table/Fig-1].

Most common clinical event recorded by us was carpopedal spasm. Around 35% of patients experienced tingling, paraesthesia and carpopedal spasm at least once in their follow-up period. This is mainly due to compliance with medication than as patient used to stop calcitriol after sometime. Documented hypocalcaemia observed in 21.7% patients, with their corrected calcium less than 8 mg%. Three patients developed drug induced hypercalcaemia which was corrected by reducing the dose of calcitriol. Two patients got admitted with renal colic and found to have ureteric stones. Both of them were managed conservatively. Ultrasound diagnosed nephrolithiasis in two patients, in whom we reduced the dose of calcitriol and followed-up every six months for disappearance of nephrolithiasis. Calcium and phosphorous levels in all patients were assessed. Two patients who had ureteric stones had their calcium phosphorous ratio more than 55, which became normal after reducing the dose of calcitriol [Table/Fig-2]. Authors have measured calcium creatinine ratio yearly in all patients, but none of them had hypercalciuria. All patients in present cohort had their calcium creatinine ratio less than 0.2 mg/dL. None of the patients progressed to renal failure.

This is one of the studies on postoperative hypoparathyroidism in which long term follow-up of patients was done both clinically and biochemically. Authors have also recorded the possible complications of both the disease and adverse effects of drugs given. Present study is unique because of regular follow-up of majority of patients and fewer complications than the studies published previously. Previously conducted studies reported higher risk of renal failure in patients with hypoparathyroidism on treatment. This is primarily due to development of hypercalcaemia and hypercalciuria arising due to treatment with calcium and calcitriol. This hypercalcaemia will lead to nephrocalcinosis or nephrolithiasis, finally resulting in renal failure. Mitchell DM et al., in his article on hypoparathyroidism reported that up to 41% of patients developed renal failure with their GFR dropping to less than 60% [13]. His study also showed that elderly patients with long standing disease and prolonged hypercalcaemia had direct correlation with impaired renal function. Decreased GFR was also observed in patients enrolled by national institute of health study [14]. None of present recorded patient developed renal failure. This may be due to smaller number of patients and may be due to frequent follow-up and monitoring of patients.

The present study also shows fluctuations of serum calcium concentrations either in the form of acute episodes of hypocalcaemia and hypercalcaemia requiring hospital admission. Most of the times, these are due to stopping of medication or excessive intake of medications. That is why frequent follow-up and monitoring of biochemical levels of calcium is of paramount important.

Authors know that nephrolithiasis and renal colic are very common in patients with hypoparathyroidism. This is mainly due precipitation of calcium salts in renal tissue due to change in ratio of calcium and phosphorous. Absence renal PTH action leads to hypercalciuria due to inefficient reabsorption of calcium and decreased secretion of phosphorous, thus facilitating nephrocalcinosis [9]. The prevalence in present cohort of patients was 8.7 percent which was comparable to 10% seen in study by Levy I et al., [14]. In another study by Mitchell DM et al., showed that in their cohort of 54 patients 31% presented either nephrolithiasis or nephrocalcinosis [13]. Surprisingly, all the patients in present cohort had their calcium creatinine ratio less than 0.2. All patients with long-term hypoparathyroidism have significant reduction in their bone remodelling. That is why patients with hypoparathyroidism have higher Bone Mineral Density (BMD) at most of the sites with highest at lumbar spine. It is also shown that hypoparathyroid patients have higher cortical and cancellous bone volumetric BMD [15]. Therefore, we rarely see bone fractures and osteoporosis in these group of patients. In present group of patients none of them had fracture till last follow-up. BMD was not measured in present study patients. A study by Underbjerg L et al., reported higher incidence of upper extremity fractures in his cohort of hypoparathyroid patients [12]. But some time overuse of calcitriol may lower bone leading to bone resorption and thus osteoporosis [12].

A similar study done by Lorente-Poch L et al., with 32 patients with hypoparathyroidism showed that 15% patients had reduced renal function and 56% patients had clinical symptom in the form of hypocalcaemia, paraesthesia, tingling and numbness [16]. They also demonstrated that there was some reduction in quality of life.

Main drawback of this study was small sample size.

Permanent Hypoparathyroidism (PH) patients on long term follow-up can present with various signs and symptoms of both hypocalcaemia and hypercalcaemia. This will lead to considerable morbidity and economic burden to the family since it is chronic disease.