Hypertonic saline test for the investigation of posterior pituitary function

• Published in: Archives of disease in childhood Vol. 79; no. 5; pp. 431 - 434
• Main Authors: Mohn, Angelika, Acerini, Carlo L, Cheetham, Timothy D, Lightman, Stafford L, Dunger, David B
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health 01.11.1998; BMJ; BMJ Publishing Group LTD; BMJ Group
• Subjects: Adolescent; Biological and medical sciences; Blood; Body Weight; Child, Preschool; Diabetes; diabetes insipidus; Diabetes Insipidus - diagnosis; Diagnosis, Differential; Diagnostic tests; disorders of water balance; Emotional Problems; Endocrinopathies; Female; Head injuries; Humans; hypertonic saline test; Hypothalamus. Hypophysis. Epiphysis (diseases); Inappropriate ADH Syndrome - diagnosis; Infant; Male; Measurement Techniques; Medical sciences; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Original; Osmosis; Patients; Pituitary Diseases - diagnosis; Pituitary Function Tests - methods; Pituitary gland; Pituitary Gland, Posterior - physiopathology; Plasma; Saline Solution, Hypertonic; Short Term Memory; Thyroid gland; Urine; Water; Water-Electrolyte Imbalance - diagnosis; England; United Kingdom; Great Britain; Europe; Endocrinopathy; Human; Urine; Plasma; Diabetes insipidus; Concentration; Differential diagnostic; Antidiuretic hormone; Hyperosmolar solution; Clinical biology; Adolescent; Pituitary diseases; Hormonal investigation; Child; Saline solution
• ISSN: 0003-9888; 1468-2044
• DOI: 10.1136/adc.79.5.431

The hypertonic saline test is a useful technique for distinguishing partial diabetes insipidus from psychogenic polydipsia, and for the diagnosis of complex disorders of osmoreceptor and posterior pituitary function. However, there is little information concerning its use in childhood. The experience of using this test in five children (11 months to 18 years) who presented diagnostic problems is reported. In two patients, in whom water deprivation tests were equivocal or impractical, an inappropriately low antidiuretic hormone (ADH) concentration (< 1 pmol/l) was demonstrated in the presence of an adequate osmotic stimulus (plasma osmolality > 295 mosmol/kg). In two children—one presenting with adipsic hypernatraemia and the other with hyponatraemia complicating desmopressin treatment of partial diabetes insipidus—defects of osmoreceptor function were identified. Confirming a diagnosis of idiopathic syndrome of inappropriate ADH secretion (SIADH) was possible in a patient with no other evidence of pituitary dysfunction. The hypertonic saline test was well tolerated, easy to perform, and diagnostic in all cases.