Abstract
In Prader–Willi syndrome (PWS), conditions that are associated with hyponatremia are common, such as excessive fluid intake (EFI), desmopressin use and syndrome of inappropriate antidiuretic hormone (SIADH) caused by psychotropic medication. However, the prevalence of hyponatremia in PWS has rarely been reported. Our aim was to describe the prevalence and severity of hyponatremia in PWS. In October 2020, we performed a retrospective study based on the medical records of a large cohort of children and adults with PWS from seven countries. Among 1326 patients (68% adults), 34 (2.6%) had at least one episode of mild or moderate hyponatremia (125 ≤ Na < 135 mmol/L). The causes of non-severe hyponatremia were often multi-factorial, including psychotropic medication in 32%, EFI in 24% and hyperglycemia in 12%. No obvious cause was found in 29%. Seven (0.5%) adults experienced severe hyponatremia (Na < 125 mmol/L). Among these, five recovered completely, but two died. The causes of severe hyponatremia were desmopressin treatment for nocturnal enuresis (n = 2), EFI (n = 2), adrenal insufficiency (n = 1), diuretic treatment (n = 1) and unknown (n = 1). In conclusion, severe hyponatremia was very rare but potentially fatal in PWS. Desmopressin treatment for nocturnal enuresis should be avoided. Enquiring about EFI and monitoring serum sodium should be included in the routine follow-ups of patients with PWS.
Highlights
Hyponatremia, defined as a serum sodium concentration below 135 mmol/L, is the most common electrolyte disorder encountered in clinical practice and has affected up to30% of hospitalized patients across numerous studies throughout the world over the last several decades [1,2]
We reported the largest cohort of patients with Prader–Willi syndrome (PWS) with a history of hyponatremia to identify the possible causes of hyponatremia and interventions to prevent the development of severe hyponatremia
Severe hyponatremia is rare in PWS (0.5%) but is potentially life threatening, with two deaths in our cohort
Summary
Hyponatremia, defined as a serum sodium concentration below 135 mmol/L, is the most common electrolyte disorder encountered in clinical practice and has affected up to30% of hospitalized patients across numerous studies throughout the world over the last several decades [1,2]. Several factors that might contribute to hospital-acquired hyponatremia have been identified, including increasing age [1], diuretics, surgery, hypotonic intravenous fluids and several drugs and diseases that promote the release of antidiuretic hormone [4]. Prader–Willi syndrome (PWS) is a rare genetic neuro-endocrine developmental disorder and the most common form of syndromic obesity with an incidence of approximately 1 in 21,000 newborns [7]. This genetic syndrome is caused by a loss of the expression of paternally inherited imprinted alleles on chromosome 15q11-q13 that can occur via three mechanisms. The main genetic mechanism is a paternal deletion in about 60%, followed by maternal uniparental disomy (mUPD) in 36% and imprinting defects in 4% of the overall
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