Case Presentation:
A 65 year old male with decompensated alcoholic cirrhosis with large right hepatohydrothorax and refractory ascites had a transthoracic echocardiogram prior to transjugular intrahepatic portosystemic shunt placement to rule out high cardiac output failure. External compression of the right atrium was noted, producing a constrictive physiology with impaired ventricular filling, septal bounce and respiratory variation in mitral inflow velocities. Placement of a pigtail drainage catheter resulted in a significant improvement in both hydrothorax and ascites. However, post procedure chest X ray showed tension pneumohydrothorax with near complete right lung collapse, requiring emergent placement of a second catheter. Five days after its placement, the second catheter migrated out of the pleural space and was exchanged with a new catheter. The pleural fluid that had been straw‐colored then turned milky. The next 24 hours saw a drainage of 2.5 L of chyle (triglyceride 252 mg/dL and cholesterol < 15mg/dL), bringing the total volume of drained pleural fluid to 13 L. On the same day, new hyperkalemia (5.8 mEq/L) and hyponatremia (126 mEq/L) developed; previously, serum K+ and Na+ were in the ranges of 4.2‐4.8 mEq/L and 130‐133 mEq/L, respectively.
Discussion:
Chylothorax in cats and dogs have been associated with hyponatremia and hypokalemia . No such association has been reported in humans. Although an interesting coincidence, chylothorax was unlikely to be directly responsible for hyponatremia and hyperkalemia in our patient. Rather, further depletion of effective circulating volume by the copious and rapid chylous drainage led to the electrolyte abnormalities: 13 L of pleural fluid had been drained when the electrolyte abnormalities developed. Chyle is a triglyceride‐rich fluid with a similar electrolyte composition as plasma. Thus, loss of chyle leads to Na+ loss and volume depletion. Supporting a state of volume deficit, urine Na+ was less than 20 mEq/L when hyperkalemia and hyponatremia first developed. Similarly, urine osmolality was greater than 100 mOsm/Kg, indicating continued ADH secretion from effective circulating volume depletion. This physiologically appropriate ADH secretion impaired water excretion, leading to hyponatremia. The sluggish distal tubular fluid delivery from volume depletion produced hyperkalemia by preventing distal K+ secretion. Adrenal insufficiency, a cause of hyponatremia and hyperkalemia, could not be excluded because morning cortisol was not measured (the goal of care was changed to comfort care). However, it is unlikely that an hitherto undiagnosed adrenal insufficiency would have suddenly manifested with these electrolyte abnormalities . The patient was not taking potassium‐sparing diuretics and his creatine remained at baseline of 0.8 mg/dL at that time.
Conclusions:
Copious and rapid chest tube drainage can result in hyponatremia and hyperkalemia by inducing a deficit in effective circulating volume.