W016

 

Hypercalcaemia in a patient on Lithium therapy

 

Dr G Das, SPR Endocrinology, Ashford and St Peters hospital, Dr Nazia Rashid, Consultant Endocrinologist, Ashford and St Peters Hospital

 

Case history: We present an interesting case of 64 years old lady who was recently referred by GP to our endocrine clinic for management of hypercalcemia. She has past medical history of Aspergerís syndrome, learning difficulties and bipolar disorder. She has no family history of hypercalcemia or nephrocalcinois. She has been on Lithium since 2011. She is asymptomatic apart from vague abdominal pain and constipation for which she has seen a gastroenterologist.

 

Hypercalcemia workup revealed corrected calcium ranging between 2.73-2.88mmol/L (normal-2.1-2.6) ,PTH-9.3 pmol/L(normal 1.5-7.6), VitD-49nmol/L(normal 75-200), ALP-69 IU/L(normal 30-130) , eGFR-55 ml/min(normal>60). Patient could not manage 24 hour urine collection due to learning difficulties. She never had bone profile tested predating Lithium start.

 

CT whole body arranged by gastroenterologist excluded malignancy, sarcoid or kidney stones. US neck however has revealed left-sided parathyroid adenoma. DEXA scan is pending. She is on Vitamin D replacement now.

 

The possible aetiology of hypercalcaemia in our case is thought to be PHPT or Lithium induced.

 

Discussion: The prevalence of LAH is estimated to range from 4.3-6.7% and is higher than overall prevalence of HPT. It is still unclear whether lithium initiates HPT or promotes an underlying subclinical state of HPT. It was shown that lithium causes a shift in the inhibitory set point for PTH secretion to a higher serum calcium concentration. It is believed to either unmask or accelerate previously unnoticed hyperparathyroidism. We review the available literature and evidence to understand the pathophysiology.Of this poorly understood endocrine disorder and also keen to learn from experiences in other centres re management.

 

Question to Panel: Should she procced with parathyroidectomy or managed conservatively?

 

References:

1) Lithium-associated hyperparathyroidism: report of four cases

And review of the literature. Auryan,Szalat1, Haggi Mazeh2 and Herbert R Freund2

2) Lithium Associated Hyperparathyroidism: An Evidence Based Surgical Approach

††† Umashankar K. Ballehaninna1,2, Steven M. Nguyen3, Ronald S. Chamberlain1,3,4