Hypo-Hypo: A Complex Metabolic Disorder

Metabolic Acidosis in Children: A Literature Review

Metabolic acidosis is characterised by a primary decrease in the serum bicarbonate concentration, a secondary decrease in the arterial partial pressure of CO­2, and a reduction in blood pH. Metabolic acidosis, acute or chronic, may have deleterious effects on cellular function and cause increased morbidity and mortality. A systematic review of the available literature was performed to identify data on the prevalence, manifestations, cause, outcomes, and treatment of metabolic acidosis in children. Online databases (Ovid Medline, Embase, and PubMed), commercial search engines (including Google), and chapters on metabolic acidosis in the standard textbooks of paediatrics and medicine were reviewed. Systematic approach to acute metabolic acidosis starts with proper history taking and examination. This is followed by assessment of acid-base parameters, including pH, partial pressure of CO2, and bicarbonate concentration in arterial blood. Blood gas is needed to differentiate primary metabolic acidosis from compensated respiratory alkalosis. Once the diagnosis of a metabolic acidosis has been confirmed, serum electrolyte values are used to determine the serum anion gap. The various causes of increased and normal anion gap metabolic acidosis have been discussed in the article. The main aim of treatment in metabolic acidosis is to reverse the primary pathophysiology. In acute metabolic acidosis, sodium bicarbonate therapy is not beneficial due to potential complications and is reserved for specific situations. Base therapy is used in chronic metabolic acidosis where it ameliorates many of its untoward effects. Other modalities of treatment of metabolic acidosis include peritoneal or haemodialysis and tris-hydroxymethyl aminomethane.

Fludrocortisone therapy for persistent hyperkalaemia

BACKGROUND

Type 4 renal tubular acidosis causes hyperkalaemia, for which diabetes and medications commonly used in this patient group are aetiological factors. Here we describe the novel use of fludrocortisone in this difficult condition.

CASE REPORT

A 55-year-old woman with complex co-morbidities, including Type 2 diabetes (HbA_1c 37 mmol/mol 5.5%), was admitted with renal failure. Bloods on admission: eGFR 25 ml/min, creatinine 184 ?mol/L, urea 35.9 mmol/L, sodium 128 mmol/L, potassium 5.6 mmol/L, bicarbonate 15 mmol/L, and albumin 30 g/L. Her admission was prolonged, complicated by hospital-acquired sepsis (lower respiratory tract, urinary tract, and infected leg ulcers), poor venous access and severe depression. She had recurrent hyperkalaemia and deteriorating renal function, from presumed Type 4 renal tubular acidosis and excessive fluid losses from leg ulcers. Her renal function recurrently deteriorated, despite conventional treatment methods. After 69 days, she was commenced on fludrocortisone 50 mcg/day. Her renal function and serum potassium stabilized and she was discharged with potassium 4.3 mmol/L, eGFR 42 ml/min, and bicarbonate 23 mmol/L. She has remained stable on this treatment, without requiring further hospital admission for over 6 months, with eGFR 40 ml/min, and potassium 5.5 mmol/L, and albumin 26 g/L.

CONCLUSION

This woman was presumed to have Type 4 renal tubular acidosis and recurrent hyperkalaemia due to renal insufficiency, in the context of underlying diabetes and chronic kidney disease, which was poorly responsive to conventional management. There is limited evidence for using fludrocortisone in this setting. Our case suggests that fludrocortisone might offer a novel therapeutic strategy when conventional management is not working.