1. A case of persistent cystinuria following resolved renal fanconi syndrome after ingestion of herbal medicines.
R. Patle1, M. Lapsley1, M. Egerton1, H. Gallagher2, A. Taylor3
1: Department of Chemical Pathology, Epsom General Hospital, Epsom, Surrey.
2: Department of Nephrology, 3: Chemical Pathology, Royal Surrey County Hospital ,Guildford.
INTRODUCTION
Renal Fanconi syndrome is characterized by proximal tubular failure to reabsorb electrolytes, bicarbonate, phosphate, amino acids, glucose, urate and low molecular weight proteins. Secondary causes of Fanconi syndrome include consumption of herbal medicines, some of which have been shown to contain heavy metals such as mercury, lead or cadmium.
CASE HISTORY CASE PROGRESS
Asymptomatic stage
EPISODE 1
A 54 year old thin built vegan on long term St Johns Wort presented in A&E on 7th July 2007 with symptoms of vomiting and history of collapse within 36 Hrs of starting a new herbal detox regimen consisting of capsules and oral drops. There was no history of diarrhoea.
Past medical:!)Spina bifida.
2)On Carbimazole for hyperthyroidism.
3)On Seretide inhaler for asthma.
No history of IHD/DM/CVA/HTN.
Serum biochemistry showed metabolic acidosis with hypophosphataemia and hypokalaemia. Urine demonstrated aminoaciduria,. (results:Chart1,2) with mildly raised retinol binding protein indicating proximal tubular injury.
Impression: herbal remedy induced renal fanconi syndrome.
Treatment: provide supplements for phosphate, potassium and bicarbonate.
Patient was followed up 4 weeks later. Clinically asymptomatic on St Johns Wort ,supplements of bicarbonate, potassium and phosphate, Carbimazole. Supplements stopped. Serum levels remained within ref range.
Urine and Serum biochemistry tests performed: Chart1,2.
The herbal remedies were analysed for the presence of acidic and basic drugs and trace/heavy metals by GCMS, EMIT, ICPMS. Results: (table).
Urine aminoacid analysis indicated reabsorption defect in dibasic aminoacids. Absolute cystine conc. Of 402 umol/L, and cystine: creatinine ratio were in range of homozygous cystinuria There was no past or family history of renal stones.
Episode 2
Patient presented in A&E(Dec 2007) with history of reduced oral intake, diarrhoea for 24 hrs not profound, no H/O vomiting.
Biochemical results similar to the first episode: Chart1,2.
Serum Mg level was within normal range in all the episodes.
Impression: Acute renal Fanconi syndrome.
Patient treated with supplements of bicarbonate and phosphate for 4 weeks. Serum biochemistry again returned back to the normal limits.
Table
Analyte
Conc. In daily dose of herbal medicines
Tolerable intake(Source:JECFA/WHO)
Arsenic
0.975ug/day
2ug/Kg/day
Cadmium
0.1ug/day
1ug/Kg/day
Mercury
45ug/day
Lead
10 ug/day
25ug/kgbw/week
Paracetamol
Not detected NA
Salicylates
Opiates
Immunosupressants
Fig: 1
Chart 2
Chart 1
DISCUSSION
Cystinuria secondary to Fanconi syndrome and classical stone forming cystinuria have been found to have different mechanisms in dog models. Possibilities in this patient include either an underlying proximal tubular defect that made her susceptible to exogenous toxins or that the acute proximal tubular disturbance resulted in longer term tubular reabsorption defects