R024

Asymptomatic severe hypercalcaemia following excessive chronic intake

Malvika Gulati, Sagen Zac-Varghese, Radha Ramachandran, Shivani Misra, Nick Oliver, Karim Meeran. Imperial Centre for Endocrinology

Abstract:

A 65 year old retired biochemist presented to A&E with a mild exacerbation of COPD. She was found incidentally to have a calcium of 4.91 (nr 2.05 – 2.60 mmol/L). She seemed extremely well and had no signs of dehydration or confusion.

She had a past medical history of laryngeal cancer and in 2003 had undergone a total laryngectomy, thyroidectomy and partial oesophagectomy with adjuvant radiotherapy. Post operatively she was hypothyroid and hypoparathyroid and was started on 125 mcg thyroxine, 1 mcg 1 alphacalcidol and 1000 mg sandocal TDS. In addition, she had been started on strontium ranelate 3 days prior to her admission.

As she was extremely well, the elevated calcium reading was thought to be spurious and was repeated. The repeat calcium and ionised calcium, measured on blood gas, remained elevated.

3 litres of normal saline were infused over 10 hours and the calcium and vitamin D supplements were withheld. The next day her calcium had improved and we were able to restart her vitamin D and calcium after 5 days.

As strontium is a 2+ ion we sought advice from the metabolic medicine physicians as to whether strontium could be interfering with the calcium assay and causing an overestimate of the calcium. However, there have been no case reports in the literature of strontium affecting calcium measurement to this order of magnitude. In addition, her measured strontium levels were in the normal range. It was felt that the COPD exacerbation had caused her to become unwell and slightly dehydrated and that this had caused a rapid increase in her calcium levels.

1 week later we reviewed the patient in our endocrine outpatients’ clinic. At this time she was on 1 mcg of 1 alpha calcidol and 3 g of calcium supplements per day. She reported feelings of pins and needles and weakness; however, no objective clinical signs of hypocalcaemia were elicited. In addition, her calcium level measured on that day was 2.85. She later admitted to an excessive calcium intake to relieve her perceived symptoms of hypocalcemia.