Letter: Hyponatraemia

Body space measurements in the hyponatraemia of carcinoma of the bronchus: evidence for the chronic 'sick cell' syndrome?

Body space measurements using simultaneous multiple isotope dilution techniques were made in both hyponatraemic and normonatraemic patients with carcinoma of the bronchus and wasting, and compared with those in a group of normal volunteers. Both groups of patients showed osmolal loss from cells. The significance of these findings in relation to the development of hyponatraemia is discussed.

Serum ionized calcium in acute pancreatitis

Measurement of serum ionized calcium was performed daily for 7 days after admission in 8 consecutive patients with acute pancreatitis. The results support the findings of our previous study that the most common cause of the low serum calcium often found in patients with this disease is a low serum albumin; when correction of serum calcium is made for hypo-albuminanemia, most patients are found to be normocalcaemic. The occasional hypocalcaemia as shown by the 'corrected' serum calcium or by serum ionized calcium measurement is usually mild and transient, indicating that the normal homoeostatic mechanisms of the body can efficiently maintain the physiologically active fraction of the serum calcium within, or close to, the normal range. These findings explain the rarity of overt and subclinical tetany in acute pancreatitis. This study has shown that correction of serum calcium for albumin provides similar information to the direct measurement of serum ionized calcium. The value of 'apparent' hypocalcemia in assessing severity of acute pancreatitis requires reappraisal, while greater attention should be directed towards the investigation and management of hypoalbuminaemia in this disease.

Prognostic value of spontaneous hyponatremia in cirrhosis with ascites

Spontaneous hyponatremia in cirrhosis with ascites is generally considered to be due to an impaired renal ability to excrete free water, to be a contraindication of diuretics, and to be a bad prognostic sign. These concepts are reviewed in this paper. 55 cirrhotics with ascites were divided into three groups. Group I consisted of 13 patients with hyponatremia and very low free-water clearance CH2O, 0.07 +/- 0.26 ml/min). These patients also had poor renal function: low inulin clearance (CINU, 40.6 +/- 25.9 ml/min) and paraaminohippurate clearance (CPAH, 383 +/- 275 ml/min). Group II consisted of 8 patients who also had hyponatremia. CH2O, CINU, and CPAH in these patients were fairly high: 5.85 +/- 1.53 ml/min, 85.7 +/- 26.2 ml/min, and 651 +/- 294 ml/min. These values are similar to those o7 +/- 4.27 ml/min, 94.7 +/- 33.1 ml/min, and 598 +/- 199 ml/min. Hyponatremia in Group I could be related to the impaired free-water clearance. The mechanism of hyponatremia in Group II patients is not clear. Patients with hyponatremia and low CINU and CPAH had a negative response to diuretics and a poor prognosis. Patients with hyponatremia but with relatively good renal function had a good prognosis, similar to Group III patients. They responded to diuretics with no worsening of their hyponatremia.

Rapid correction of water intoxication by hypertonic saline and frusemide

A case of profound hyponatraemia with severe cerebral dysfunction, induced by excess water intake and exacerbated by smoking, is described. Rapid correction with hypertonic saline infusions and frusemide allowed a negative fluid balance and elevation of serum sodium concentration to be achieved without precipitating acute pulmonary oedema.