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Type 1 renal tubular acidosis presenting with recurrent hypokalaemia paralysis
*Corresponding author: Akshai B. Mariyil, Department of General Medicine, Sri Siddhartha Medical College Hospital and Research Center, Tumakuru, Karnataka, India. akshaibmariyil@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Mariyil AB, Shankarappa RS. Type 1 renal tubular acidosis presenting with recurrent hypokalaemia paralysis. Karnataka Med J. 2025;48:68-70. doi: 10.25259/KMJ_18_2024
Abstract
Type 1 renal tubular acidosis (RTA) is a metabolic disease characterised by hypokalaemia, hyperchloremic metabolic acidosis and urine pH above 5.5. These findings may be accompanied by hypercalciuria, nephrocalcinosis, nephrolithiasis, jaundice, osteomalacia or rickets in children. Although hypokalaemia is frequently seen as a laboratory finding in Type 1 RTA, weakness, which is the clinical finding of this deficiency, is rare. A 60-year-old female patient was brought to the emergency department with complaints of weakness, loss of strength in the extremities and difficulty in breathing. Laboratory analyses of the patient revealed metabolic acidosis and hypokalaemia. Urea and creatinine values were normal. The patient was admitted to the internal medicine department with a preliminary diagnosis of Type 1 RTA and hypokalaemic paralysis. Initially, parenteral infusion of KCl and NaHCO3 was administered in the treatment. In the follow-up of the patient, it was observed that hypokalaemia and metabolic acidosis improved within 48 h following the replacement therapy. Type 1 RTA, which is rare in adults, is among the secondary causes of hypokalaemic paralysis. Type 1RTA should be considered among the differential diagnoses in the presence of hypokalaemia and metabolic acidosis in patients presenting with bilateral weakness.
Keywords
Acidosis
Elderly
Hypokalaemia
Renal tubular acidosis
Weakness
INTRODUCTION
Hypokalaemia is an Elyte characterised by low serum potassium concentrations (normal range: 3.5– 5.0 mEq/L). Hypokalaemia can be caused either by decreased intake of potassium or by excessive losses of potassium in the urine or through the gastrointestinal (GI) tract. Excessive excretion of potassium in the urine (kaliuresis) may result from the use of diuretic drugs, endocrine diseases such as primary hyperaldosteronism, kidney disorders and genetic syndromes affecting the renal function.[1] Renal tubular acidosis (RTA) is defined as an inability of the renal tubule to acidify urine, which is out of proportion to any reduction in the glomerular filtration rate. In the presence of normal anion gap metabolic acidosis, RTA should be considered. RTA Types 1 and 2 are seen with hypokalaemia, while RTA Type 4 is associated with hyperkalaemia and the manifestations of Type 4 RTA are a consequence of the effects of aldosterone deficiency or insensitivity. Type 1 RTA is associated with reduced urinary acid secretion, Type 2 RTA is characterised by impaired bicarbonate (HCO3) reabsorption.[2] Type 1 distal RTA is due to absent or decreased activity of H+-ATPase of intercalated cells located in collecting tubules of distal nephron which may play role in the pathogenesis. Classically, Type 1 RTA is characterised by hyperchloremic metabolic acidosis and a defect in urinary acidification, which may be associated with hyper calcinuria, hypocitraturia, nephrolithiasis, nephrocalcinosis, hypokalaemia, progressive renal failure and growth retardation, Type 1 RTA is characterised by urinary pH above 5.5.[3] Clinically, it may present with non-specific findings such as constipation, weakness, growth retardation in childhood, nausea-vomiting, polyuria-dehydration as well as presentations with complications related to the kidney and musculoskeletal system.[4] Hypokalaemic paralysis is an uncommon, life-threatening syndrome with widespread muscle weakness, including respiratory muscles, if it is diagnosed and treated appropriately, it resolves without sequelae. Periodic paralysis is distinguished by a normal potassium level, except for attacks. Hypokalaemia periodic paralysis may be primary or secondary to thyrotoxicosis, primary hyper aldosteronism, Type 1 RTA, GI disorders and barium intoxication. Hypokalaemic paralysis is a common manifestation of RTA in some parts of the world.[5]
CASE REPORT
A 60-year-old female presented to the emergency room with a history of sudden onset weakness of all her limbs (proximal > distal) for 5 h rapidly progressed in such a way that the patient was not able to get up from bed and walk and also give history of constipation for 2 days. The patient also gives a history of a heavy carbohydrate meal 2 days before the symptoms. The patient experienced a similar episode of weakness in her lower limbs > upper limb about 1 year earlier and was diagnosed as hypokalaemia paralysis, and she was treated with potassium chloride which resulted in a total recovery over a period of 48 h. There was no preceding viral illness, drug intake or diarrhoea, vomiting, fever, breathlessness, palpitation, dryness of mouth or eyes. Clinical examination shows that the patient was conscious, oriented, pulse rate was 76/min, regular rhythm, blood pressure 110/70 mm Hg, respiratory rate –18/min and SpO2-100% on room air. Central nervous system examination showed normal higher mental function, cranial nerve examination with in normal limit and motor system examination showed hypotonia of both upper and lower limb. Power of the bilateral proximal upper limb 2/5, and distal upper limb 3/5 and power of bilateral proximal lower limb 2/5 and distal lower limb is 3/5. Reflexes of lower limb ankle and knee jerk grade 0 bilaterally. Upper limb reflex showed bicep, supinator, triceps reflex was grade 1 and bilateral plantar was mute. Sensory system examination is normal, P/A – soft and non-tender bowel sound absent. Respiratory system – normal vesicular breath sounds heard bilaterally and no added sound. Cardiovascular system examination showed normal S1 and S2 and no added sounds. Electrocardiogram shows a normal sinus rhythm with U wave. Preliminary investigations were within normal limits except a serum potassium level of 1.8 mmol/L, arterial pH of 7.27, pCO2 27.8, pO2 89.1 and bicarbonate level of 13.5 mmol/L (hypokalaemia with normal anion gap metabolic acidosis). The patient was started on 40 mEq of potassium chloride over 4 h, still the repeat serum potassium was 1.8 mmol/L. Hence, 1 more 40 mEq of potassium chloride was given over 4 h and the weakness recovered over the next 48 h and the patient passed stools. Subsequent investigations revealed that the hemogram was normal. Serum urea was 36 mg/dL, creatinine level 1 mg/dL, glucose 115 mg/dL, calcium 9 mg/dL and serum magnesium −2.6 mg/dl. Serum sodium was 140 mmol/L, potassium 2.4 mmol/L and chloride 108 mmol/L. Serum levels of T3, T4 and thyroid-stimulating hormone were normal, and hepatitis B surface antigen and hepatitis C virus are non-reactive. Schirmer test for lacrimation was normal. Ultrasound examination of the abdomen was normal. The radiograph of the chest was normal. Urine was negative for glucose, protein or blood, and the microscopy was normal. Urine pH was 6, urine anion gap 5.9 and urine potassium of 7.9 mmol/L. Urinary excretion of calcium, creatinine, uric acid and phosphates was normal. The patient was discharged on oral sodium bicarbonate and has been weakness free over a follow-up.
DISCUSSION
In our case, 60-year-old female came with a sudden onset proximal muscle weakness, based on the clinical examination showing weakness of all 4 limbs hyporeflexia, constipation and the laboratory values of potassium <2 mEq/mL suggesting severe hypokalaemia, a diagnosis of transient hypokalaemia paralysis was made. There was also a drastic improvement in symptoms after potassium supplementation. Based on urinary examination showing increased fractional excretion of potassium along with arterial blood gas analysis findings showing metabolic acidosis, with alkaline urinary pH a diagnosis of type 1 RTA was made. All patients diagnosed with RTA should be investigated for other diseases that may cause RTA. Our patient’s clinic and examinations are not compatible with collagen tissue diseases in terms of diseases that may cause Type 1 RTA, and she did not use any drugs or herbs. Failure to define family history caused the case to be evaluated as sporadic. In addition to the treatment of the pathology causing distal RTA, HCO3 and K+ replacements are also necessary. We also prescribed bicarbonate and potassium preparations for distal RTA. Distal RTA is characterised by a failure of H+ secretion into lumen of nephron by the alpha intercalated cells of the medullary collecting duct of the distal nephron. This failure of acid secretion may be due to a number of causes, and it leads to an inability to acidify the urine to a pH of <5.3. Because renal excretion is the primary means of eliminating H+ from the body, there is consequently a tendency toward acidemia. There is an inability to excrete H+ while K+ cannot be reclaimed by the cell, leading to acidemia (as H+ builds up in the body) and hypokalaemia (as K+ cannot be reabsorbed by the alpha cell). This leads to the clinical features of dRTA in other words, the intercalated cells apical H+/K+ antiporter is non-functional, resulting in proton retention and potassium excretion.[4]
CONCLUSION
Electrolyte disturbances, especially hypokalaemia, should be considered in patients presenting to the ED with bilateral weakness. The possibility of Type 1 RTA, which is rare in adults, should be considered in cases presenting to the ED with paresis in the extremities with or without respiratory distress.
Authors’ contributions:
ABM, RSS: Both authors were involved in the diagnosis of the case, treatment, and preparation of the manuscript.
Ethical approval:
Institutional Review Board approval is not required.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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