A study of serum antidiuretic hormone and atrial natriuretic peptide levels in a series of patients with intracranial disease and hyponatremia.

Patients with intracranial disease are at risk of developing clinical deterioration due to a hyponatremic syndrome associated with an inappropriate degree of natriuresis, the "syndrome of inappropriate secretion of anti-diuretic hormone (ADH)" or SIADH. To investigate the hypothesis that atrial natriuretic peptide (ANP) is related to the natriuresis in SIADH, serum samples were obtained from 8 neurosurgical patients with intracranial disease seen consecutively who fulfilled the traditional clinical and laboratory criteria for SIADH. In one patient with a hemorrhagic cerebral infarction an elevation of serum ADH (5.7 pg/ml; normal = 1 to 5 pg/ml) in association with a normal level of serum ANP (49.8 pg/ml; normal = 10 to 60 pg/ml) was seen. Six patients (2 with intracerebral hemorrhage and 1 with hemorrhagic cerebral infarction, 1 with aneurysmal subarachnoid hemorrhage, 1 with glioblastoma multiforme, and 1 with Creutz-feldt-Jakob disease) had elevated serum ANP levels (197.0, 112.0, 92.0, 432.0, 97.5, and 138.0 pg/ml, respectively) associated with either normal or low ADH levels (1.3, 2.5, 1.2, 0.7, 2.3, and 0.5 pg/ml, respectively). Another patient with an intracerebral hemorrhage had a normal serum ANP level (37.0 pg/ml) and undetectable ADH level (less than 0.5 pg/ml). In the 7 patients in whom either ADH or ANP alone was elevated, a reciprocal relationship was observed between serum ADH and ANP levels, which could be expressed in logarithmic form (correlation coefficient, r = 0.727). In the 6 patients in whom serum ANP level alone was elevated, a near linear relationship was observed between serum ANP levels and urine sodium excretion (r = 0.851).(ABSTRACT TRUNCATED AT 250 WORDS)