Hyponatremia in intracranial disease: perhaps not the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)

Abstract

Patients with intracranial disorders are prone to develop hyponatremia with inability to prevent the loss of sodium in their urine. This was originally referred to as "cerebral salt wasting," but more recently is thought to be secondary to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Blood volume determinations were made in 12 unselected neurosurgical patients with intracranial disease who fulfilled the laboratory criteria for SIADH. Ten of the 12 patients had significant decreases in their red blood cell mass, plasma volume, and total blood volume. The finding of a decreased blood volume in patients who fulfill the laboratory criteria for SIADH is better explained by the original concepts of cerebral salt wasting than by SIADH. The primary defect may be the inability of the kidney to conserve sodium.

Syndromes related to sodium and arginine vasopressin alterations in post-operative neurosurgery

“…the incidence of csWs among all the patients was greater than that of sIADH, which is in agreement with reports from various other authors, who also observed a greater prevalence of csWs, compared to sIADH in neurological patients 1,2,4,5,10,18,30 . the coexistence of DI and csWs (mixed syndrome) observed in our patients has also been described by yamaki et al 17 , who studied two patients postoperatively following surgery for pituitary tumor and observed the presence of severe natriuresis and hyponatremia in a study patient who developed DI (fluid loss >2.36 ml/kg/h), which led the authors to conclude that hyponatremia resulting from csWs in intracranial diseases may develop in patients with DI.…”

“…Improved knowledge with respect to the physiology of arginine vasopressin (AVP), the possibility of its measuring by radioimmunoassay 2,[16][17][18][19][20][21] and the report of hypovolemia in the majority of neurological patients presenting hyponatremia and natriuresis, led investigators to question sIADH in brain disease. Many questions remain unanswered with respect to sIADH since few studies in which AVP was measured have been reported and results have been contradictory 1,2,7 . At the present time, csWs has again been proposed as a cause of hyponatremia associated with neurological disease.…”

“…Initially, hyponatremia in patients with intracranial disease was attributed to cerebral salt wasting syndrome (csWs), as proposed by Peters et al in 1950 13 . later, the syndrome of inappropriate antidiuretic hormone secretion (sIADH), described by schwartz et al in 1957 14 , became accepted as the principal cause of hypona-tremia in neurological patients with excessive urinary sodium loss, and the original concept of csWs was abandoned 1,8,[14][15][16][17] . Hypernatremia is the sodium disturbance least frequently found in these patients and its principal cause is neurogenic diabetes insipidus.…”

“…At the present time, csWs has again been proposed as a cause of hyponatremia associated with neurological disease. the majority of patients diagnosed with sIADH are hypovolemic and, when treated with fluid restriction, may develop a stroke with consequent worsening of their neurological condition 18 , suggesting that csWs may be the most probable cause of hyponatremia in these patients 1,2,4,5,7,16,19 . other studies suggest that hyponatremia may be iatrogenic, secondary to the excessive administration of hypotonic liquids 20 .…”

“…Alterations in sodium are frequently found in neurological and neurosurgical patients [1][2][3][4][5][6][7] and are associated with alterations in the osmolarity of the extracellular medium and changes in the volume of the cells of the central nervous system (cNs). they may aggravate the condition of these patients 8 .…”