We have read with great interest the paper of Plouin et al. [1] about the trends in the prevalence of primary aldosteronism, aldosterone-producing adenomas and surgically correctable aldosterone-dependent hypertension. We would like to reiterate that primary aldosteronism occasionally presents with a dramatic clinical picture necessitating emergency therapy. An unusual case of a 31-year-old Caucasian female patient, who was admitted to hospital as an emergency case in complete paralysis of all four limbs, is reported. During the previous 4 months she had been complaining of fatigue, muscle weakness, cramps, polydipsia, polyuria and nocturia, but she had not visited a doctor. The night before the admission she went to bed without any additional symptoms and was woken up a few hours later by a severe headache and realized that she could not move her hands or legs. The clinical examination revealed flaccid paralysis of the hands and legs, blood pressure 200/115 mmHg and heart rate 124 beats/min. Serum potassium was 1.9 mEq/l, serum sodium 146 mEq/l, serum bicarbonate 32 mEq/l and 24 h urinary potassium excretion 58 mEq. The remaining routine laboratory tests were normal. The chest X-ray film showed cardiomegaly, the 12-lead electrocardiogram sinus tachycardia and the 2D-Doppler echocardiogram left ventricular hypertrophy. Plasma aldosterone (PA) was 92 ng/dl, plasma renin activity (PRA) was less than the lower limit of detection of our assay (0.35 ng/ml1 h1) and the plasma aldosterome/plasma renin activity ratio (ARR) was well above the cut-off level of 30 ng/dl/ng ml1 h1. The acute intravascular volume expansion with the intravenous administration of isotonic saline, at a rate of 500 ml/h for 4 h, showed autonomous aldosterone production (PA: pre = 97.9, after 2 h = 92.8, after 4 h = 116.6 ng/dl; PRA: pre = 0.06, 2 h = 0.06, 4 h = 0.04 ng/ml1 h1). The above results were considered diagnostic of primary aldosteronism. A computerized tomography scan with fine cuts (2.53 mm) showed a nodule of 1.8 cm in diameter in the left adrenal and thickening of the right adrenal limbs. To investigate the possibility that the nodule could be a part of bilateral adrenal gland hyperplasia, adrenal venous sampling was performed. Adrenal vein cannulation disclosed a cortisol level in the left adrenal vein of 490 µg/dl and in the right adrenal vein of 520 µg/dl, whereas in the inferior vena cava (IVC) the level was 29 µg/dl. The left adrenal vein/IVC cortisol ratio was 16.8, while that in the right side was 17.9. The cannulation was considered successful because the adrenal vein/IVC cortisol gradient was more than 5 in both sides. The aldosterone level in the left adrenal vein was 890 ng/dl and in the right one was 510 ng/dl. The aldosterone/cortisol ratio in the left adrenal vein was 1.81, in the right one was 0.98 and the left/right ratio was 1.84, which is considered to be diagnostic of bilateral adrenal hyperplasia [2,3].
Intravenous potassium supplementation began immediately, leading to a rapid improvement of clinical symptoms. Spironolactone 100 mg t.d.s. was administered and in the following days normokalaemia was restored and blood pressure fell to normal levels. Potassium supplementation ceased and spironolactone was reduced gradually and was maintained at 25 mg t.d.s. After her discharge, the patient was followed as an outpatient and her general condition remained excellent with normal blood pressure 125/80 mmHg and serum potassium 4.2 mEq/l.
Hypokalaemia is usually well tolerated in otherwise healthy people, but it can be life-threatening when severe [4]. On the other hand, the clinical symptoms of primary aldosteronism are often absent or non-specific. Spontaneous hypokalaemia in a patient with hypertension is a strong indicator that primary aldosteronism is present. However, at least 20% of patients have a low normal potassium level. Aldosterone-induced renal potassium wasting is diminished by decreased sodium delivery to the distal nephron and some patients may have normal potassium levels, possibly because of self-selected dietary sodium restriction. As our patient was not aware of being hypertensive, she was apparently having a salt-free diet, which is the only possible cause of the excessive hypokalemia. In addition, other hypertensive patients may have hypokalemia as a result of diuretic therapy, liquorice ingestion, secondary aldosteronism or other syndromes associated with mineralocorticoid excess [5]. Hypokalaemic paralysis is more common in Asia, especially in China, and few cases have been reported in Western countries [68]. In conclusion, hypokalaemic paralysis may be due to different causes, but in combination with hypertension it may raise the suspicion of primary aldosteronism.
Conflict of interest statement. None declared.
Second Propedeutic Department of Internal Medicine Aristotle University of Thessaloniki Hippokration Hospital Greece Email: astkar{at}med.auth.gr
References