To the editor: Acute renal infarction results  from  renal  artery  occlusion  by embolic  or  thrombotic  events.1 Renal embolism is most commonly caused by thrombi  released  from  the  heart  in  patients with heart disease. Thrombosis is usually due to trauma, or to generalized atherosclerosis  in  elderly  patients.  A less common cause are hypercoagulability  states,  associated  to  an  increased risk  of  venous,  or more rarely  arterial, thrombosis.  Such  association  is  stronger  in  patients  aged  < 55 years  and women.2



The  case  of  a  48-year-old  male  patient whose father had died from a stroke is reported. The patient had a personal  history  of  HBP,  dyslipidemia  and former  smoking.  In  1994  he  experienced  an  inferolateral  non-Q  wave AMI, and in 2001 he was admitted to hospital for  an  ischemic  stroke.  He  was  then diagnosed a mutation in  the prothrombin  (FII  20210)  and  methylenetetrahydrofolate  reductase  (MTHFR)  genes, with  normal  homocysteine  levels.  Patient was again  admitted  to  hospital  in 2002  for  non-Q  wave  AMI.  He  was being treated wit ramipril, acetyl salicylic  acid,  omeprazole,  pravastatin,  and metoprolol.



He  attended  the  emergency  room for  a  sudden,  continuous  pain  in  the periumbilical  region  and  right  flank

for  the  past  72  hours.  Pain was  irradiated  to  the  right  renal  fossa and associated to nausea, vomiting, and dark urine.



Physical examination revealed abdominal  tenderness  in  the  periumbilical region and right flank.



Laboratory  tests  showed  elevated GOT, GPT,  and LDH levels  with  normal renal function, electrolytes, and coagulation. Urine analysis found proteinuria (30 mg/dL). Chest and abdominal X-rays were unremarkable.



An urgent abdominal CT scan with contrast  revealed  patchy  hypodense areas  in  the  right  kidney  consistent

with renal  infarction (fig. 1). The patient was  admitted  to  the  nephrology department,  where  anticoagulation

with low molecular weight heparin at therapeutic doses was  started. Subsequent measurements  of  vitamin B12,

folate, antinuclear and antiphospholipid  antibodies,  tumor  markers,  and lipid  metabolism  were  all  normal.

Diagnosis  of  mutation  in  the  FII 20210  gene  (heterozygous)  and  the MTHFR  gene  (homozygous)  was

confirmed, with  homocysteine  levels in  the  upper  normal  range.  The  thrombophilia study was otherwise normal. A 99m-Tc-DTPA perfusion study showed  a  triangular  uptake  defect  in the  upper  pole  of  the  right  kidney consistent with renal infarction. A 99-Tc-DMSA renal scan confirmed diagnosis.



Patient  had  a  favorable  course, with  disappearance  of  pain  and  gradual  decrease  in  LDH.  Heparin  was

replaced by acenocoumarol for an indefinite  time,  and  folic  acid  was added due to the finding of homocysteine  levels  in  the  upper  normal range.



Rapid diagnosis of renal infarction is  critical  if  thrombolysis  or  surgery is to be attempted to preserve kidney

function.  There  are  several  helpful tests  for  diagnosis,  and  the  choice depends on  test availability. CT with

a  contrast  agent  provides  a  fast,  accurate  diagnosis.  Isotope  flow  imaging  with  DTPA-Tc99m shows  an  absent  or  decreased  perfusion  in  the affected  kidney.  Doppler  ultrasound has a limited value, and renal arteriography  is  the  definitive  diagnostic procedure.



Mutation  in  the FII  20210  gene  is associated to a 30% increase in baseline  prothrombin  levels  that  predisposes to thrombotic events. Hyperhomocysteinemia may be  congenital or acquired. Acquired  forms  are  secondary  to  folate  or  vitamin B12  or B6 deficiency. Congenital  forms are due to  mutations  in  the  cystathionine-b-synthetase gene or the MTHFR gene, more common, and which is associated  to hyperhomocysteinemia  particularly  in  homozygotes  with  folate deficiency.  Hyperhomocysteinemia predisposes  to  thrombotic  events  by endothelial  activation,  muscle  cell proliferation, and changes in NO production  or  sterol  metabolism  in  endothelium.3



Absence  of  hyperhomocysteinemia in  this  patient  with  MTHFR  mutation was possibly due to the fact that he was

never detected vitamin B12 or B6 or folate deficiency.



Thrombophilia should be searched in patients  with  recurrent  venous  thrombotic  events.  However,  such  search

does  not  appear  to  be  indicated  in  patients with isolated arterial thrombosis, especially  if  they  have  risk  factors  for arterial disease.



The risk of venous thrombosis in patients with FII 20210 or MTHFR mutation is low. Its role in arterial thrombosis is unclear, with a slight risk of AMI or stroke occurrence. An increased risk exists  in  patients  aged  <  55  years  and

female patients, with a more significant effect if concomitant coagulation disorders and associated cardiovascular risk factors exist.4



As  to  therapeutic  management, prophylaxis  should  be  started  in asymptomatic  patients  or  patients with  thrombosis associated  to  risk  situations,  and  indefinite  anticoagulation  should  be  given  to  patients with

two or more spontaneous thromboses, life-threatening thrombosis, or thrombosis  linked  to more  than one genetic

abnormality.



In  our  case,  the  patient  was  <55 years, and had FII 20210 and MTHFR mutations and cardiovascular risk factors  (HBP,  former  smoker,  drinker). Management would have required the previous start of  indefinite anticoagulation  that would  have  prevented  the occurrence  of  a  third  thrombotic event.5



The interest of the reported case lies in the occurrence of renal infarction in a patient with mutation in the FII 20210

and MTHFR genes, a previously unreported clinical condition.