Ranawaka Randula, Dayasiri Kavinda, Gamage Manoji
Department of Paediatrics, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo 8, Sri Lanka.
Professorial Paediatric Unit, Lady Ridgeway Hospital for Children, Colombo 08, Sri Lanka.
BMC Res Notes. 2017 Nov 25;10(1):618. doi: 10.1186/s13104-017-2949-2.
Distal (Type 1) renal tubular acidosis (dRTA) is characterized by inability to secrete hydrogen irons from the distal tubule. The aetiology of dRTA is diverse and can be either inherited or acquired. Common clinical presentations of dRTA in the paediatric age group include polyuria, nocturia, failure to thrive, constipation, abnormal breathing and nephrolithiasis. Though persistent hypokalemia is frequently seen in dRTA, hypokalemic muscular paralysis is uncommon and rarely described in children.
Three and a half years old girl was referred for evaluation of progressive loss of gross motor milestones over 6 months and acute episode of paralysis. Her other developmental domains were age appropriate. Notably, there was no history of polyuria, polydipsia, nocturia and abnormal breathing. Physical examination revealed proximal myopathy (waddling gait and positive Gower's sign), diminished lower limb reflexes and muscle tone. Her serum potassium was low (2.1 meq/l) and she was subsequently investigated for hypokalemic paralysis. Diagnosis of distal renal tubular acidosis was made, based on hypokalemic hyperchloremic metabolic acidosis with normal anion gap, high urine pH, borderline hypercalciuria, medullary nephrocalcinosis and exclusion of other differential diagnosis. The child showed complete symptomatic recovery upon commencement of standard treatment for distal renal tubular acidosis.
This case report highlights the importance of considering hypokalemia and renal tubular acidosis in the differential diagnosis of acute flaccid paralysis and proximal myopathy. Early diagnosis will prevent costly investigations and enable rapid clinical recovery in the affected child.
远端（1型）肾小管酸中毒（dRTA）的特征是远端肾小管无法分泌氢离子。dRTA的病因多种多样，可遗传或后天获得。小儿年龄组dRTA的常见临床表现包括多尿、夜尿、生长发育迟缓、便秘、呼吸异常和肾结石。虽然dRTA中经常出现持续性低钾血症，但低钾性肌肉麻痹并不常见，在儿童中很少有描述。
一名3岁半女孩因6个月来粗大运动里程碑的逐渐丧失和急性麻痹发作前来评估。她的其他发育领域与年龄相符。值得注意的是，没有多尿、多饮、夜尿和呼吸异常的病史。体格检查发现近端肌病（鸭步和戈尔征阳性）、下肢反射和肌张力减弱。她的血清钾低（2.1meq/l），随后对她进行了低钾性麻痹的检查。根据低钾性高氯性代谢性酸中毒伴正常阴离子间隙、高尿pH值、临界高钙尿症、髓质肾钙质沉着症以及排除其他鉴别诊断，诊断为远端肾小管酸中毒。在开始对远端肾小管酸中毒进行标准治疗后，患儿症状完全恢复。
本病例报告强调了在急性弛缓性麻痹和近端肌病的鉴别诊断中考虑低钾血症和肾小管酸中毒的重要性。早期诊断将避免昂贵的检查，并使患病儿童迅速临床康复。
