Diagnosis and Treatment > Signs and Symptoms
Thyroid Research Group, Division of Infection and Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff, UK
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Thyroid Research Group, Division of Infection and Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff, UK
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Institute of Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, UK
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Summary
Hyponatraemia is the most commonly encountered electrolyte disturbance in neurological high dependency and intensive care units. Cerebral salt wasting (CSW) is the most elusive and challenging of the causes of hyponatraemia, and it is vital to distinguish it from the more familiar syndrome of inappropriate antidiuretic hormone (SIADH). Managing CSW requires correction of the intravascular volume depletion and hyponatraemia, as well as mitigation of on-going substantial sodium losses. Herein we describe a challenging case of CSW requiring large doses of hypertonic saline and the subsequent substantial benefit with the addition of fludrocortisone.
Learning points:
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The diagnosis of CSW requires a high index of suspicion. Distinguishing it from SIADH is essential to enable prompt treatment in order to prevent severe hyponatraemia.
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The hallmarks of substantial CSW are hyponatraemia, reduced volume status and inappropriately high renal sodium loss.
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Substantial volumes of hypertonic saline may be required for a prolonged period of time to correct volume and sodium deficits.
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Fludrocortisone has a role in the management of CSW. It likely reduces the doses of hypertonic saline required and can maintain serum sodium levels of hypertonic saline.
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Summary
Type 1 pseudohypoaldosteronism (PHA) is a rare heterogeneous group of disorders characterised by resistance to aldosterone action. There is resultant salt wasting in the neonatal period, with hyperkalaemia and metabolic acidosis. Only after results confirm isolated resistance to aldosterone can the diagnosis of type 1 PHA be confidently made. Type 1 PHA can be further classified into i) renal type 1 (autosomal dominant (AD)) and ii) multiple target organ defect/systemic type 1 (autosomal recessive (AR)). The aim of this case series was to characterise the mode of presentation, management and short-term clinical outcomes of patients with PHA type 1. Case notes of newly diagnosed infants presenting with PHA type 1 were reviewed over a 5-year time period. Seven patients were diagnosed with PHA type 1. Initial presentation ranged from 4 to 28 days of age. Six had weight loss as a presenting feature. All subjects had hyperkalaemia, hyponatraemia, with elevated renin and aldosterone levels. Five patients have renal PHA type 1 and two patients have systemic PHA type, of whom one has had genetic testing to confirm the AR gene mutation on the SCNN1A gene. Renal PHA type 1 responds well to salt supplementation, whereas management of patients with systemic PHA type 1 proves more difficult as they are likely to get frequent episodes of electrolyte imbalance requiring urgent correction.
Learning points
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Patients with type 1 PHA are likely to present in the neonatal period with hyponatraemia, hyperkalaemia and metabolic acidosis and can be diagnosed by the significantly elevated plasma renin activity and aldosterone levels.
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The differential diagnosis of type 1 PHA includes adrenal disorders such as adrenal hypoplasia and congenital adrenal hyperplasia; thus, adrenal function including cortisol levels, 17-hydroxyprogesterone and a urinary steroid profile are required. Secondary (transient) causes of PHA may be due to urinary tract infections or renal anomalies; thus, urine culture and renal ultrasound scan are required respectively.
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A differentiation between renal and systemic PHA type 1 may be made based on sodium requirements, ease of management of electrolyte imbalance, sweat test results and genetic testing.
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Management of renal PHA type 1 is with sodium supplementation, and requirements often decrease with age.
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Systemic PHA type 1 requires aggressive and intensive fluid and electrolyte management. Securing an enteral feeding route and i.v. access are essential to facilitate ongoing therapy.
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In this area of the UK, the incidence of AD PHA and AR PHA was calculated to be 1:66 000 and 1:166 000 respectively.
