Endocrine Abstracts

JOINT2001

Primary hyperparathyroidism(PHPT) is a common endocrinological disorder causing hypercalcaemia, with potential complications affecting bones and kidneys. Diagnosis requires exclusion of secondary causes, and management typically involves parathyroidectomy. Cinacalcet is an alternative for a selected group of patients, necessitating careful patient selection and biochemical monitoring. This study evaluates the adequacy of PHPT diagnostic workup and the efficacy of Cinacalcet prescribing and monitoring in PHPT patients.

Methods: A retrospective audit was conducted in a single-centre endocrinology outpatient clinic, reviewing 42 patients with PHPT prescribed cinacalcet. Data on diagnostic work-up, cinacalcet initiation criteria, calcium monitoring, and treatment outcomes were analysed.

Results: While PHPT was confirmed in all patients (n =42), diagnostic work-up revealed that urinary calcium assessment was performed in 61.9% of patients with clinical suspicion of familial hypocalciuric hypercalcaemia. Most patients (n =38) had vitamin D measured as part of their assessment. Screening for end-organ damage using DEXA scan and ultrasound and/or CT KUB was performed in 93% of patients, with 40% showing evidence of complications. Regarding calcium levels, 47.6% of patients had serum calcium levels ≥2.85 mmol/l with symptoms, while 33.3% had levels >3 mmol/l. A small proportion (n =8) were started on cinacalcet for symptomatic PHPT despite having serum calcium <2.85 mmol/l. Overall compliance with prescribing criteria was 66.7%. Importantly, none of the patients developed hypocalcaemia during treatment. At initiation, mean serum calcium was 2.93 mmol/l, decreasing to 2.69 mmol/l at one month following starting cinacalcet, with further reduction to 2.49 mmol/l in patients achieving normalisation. However, 23% had persistently elevated calcium despite treatment.A weak negative correlation was observed between cinacalcet starting dose and calcium levels at one month (ρ=-0.30,P = 0.061), and no significant correlation with final calcium normalisation (ρ=0.068,P = 0.58). 35.7% of patients had serum calcium checked at one week after starting cinacalcet, while 61% had testing every 2-3 months. Overall compliance with BNF monitoring guidelines was 21.4%, with only 14.3% of patients meeting both prescribing and monitoring standards. No significant association was found between monitoring frequency and calcium normalisation (P = 0.127).

Conclusion: Our study shows that Cinacalcet effectively reduces serum calcium in PHPT. Monitoring of serum calcium during cinacalcet treatment could be more robust, to assess its efficacy and safety. The weak correlations between the starting dose of cinacalcet and serum calcium levels indicate that the current dosing strategy may not fully account for the variability in response to treatment. Further research is needed to identify potential barriers to optimal prescribing and monitoring, and develop targeted interventions to improve adherence and patient safety. We would like to acknowledge Alexander Jones, Clinical Pharmacist, for their invaluable contribution to this audit by providing a list of patients who were dispensed Cinacalcet by the hospital pharmacy between 2017 and 2024, including the dates of dispensing, and quantities dispensed.