Restless leg syndrome as a complication of primary hyperparathyroidism: insights from a retrospective study

Restless leg syndrome (RLS) is an invalidating neurological disorder with a complex, largely unknown pathophysiology. While RLS is observed in Parkinson's disease and in renal failure, idiopathic cases are common. Limited reports associate RLS with parathyroid hormone (PTH). This study analyzes a cohort of patients with primary hyperparathyroidism (PHPT) and chronic post-surgical hypoparathyroidism (hypo PTH), to investigate RLS prevalence, and associated risk factors.

Ninety-five patients (54 PHPT, 41 hypo PTH) were consecutively enrolled at the bone metabolism outpatient clinic. The revised IRLSSG diagnostic criteria were used to diagnose RLS, with assessments conducted through face-to-face interviews and neurological examination. When RLS was confirmed, the RLS severity scale was applied. Retrospective records included calcium-phosphate metabolism-related parameters, surgery details, renal lithiasis, fragility fractures, and densitometric features (T-score).

RLS was diagnosed in 22.2% PHPT patients, compared to 4.9% of patients with hypo PTH (p = 0.02). Of RLS diagnosed patients, 91.7% had a history of parathyroidectomy, compared to 47.6% of patients without RLS (p = 0.01). Most of the operated patients reported that surgery determined an improvement of symptoms; however, mean score severity of RLS at our evaluation was 15/40, defined as moderate. PTH and calcium levels were not statistically associated to the presence of RLS.

Our study suggests that PHPT may be one of the etiologies of RLS. Parathyroidectomy alleviates symptoms in the vast majority of the cases but does not remove them.