Sequential Evaluation of Erythrocyte Zinc Protoporphyrin in a Dog with Polycythemia Submitted to Phlebotomies
C.S. Prosser; M.M. Kogika; D.M.N. Simões; K.K. Kanayama; P.R.E. Mosko; M.B. Silva; M.F. Waki; A. Alves
Support by FAPESP (Process # 06/57928-1).
Polycythemia is characterized by an increased red blood cell count and PCV, and it is classified as relative or absolute; relative occurs in case of dehydration and hemoconcentration and absolute is divided in primary or secondary. The primary is a myeloproliferative disorder with normal erythropoietin (EPO) concentrations, and the secondary is EPO dependent. Phlebotomies are indicated for the treatment of absolute polycythemia and it may cause loss of iron; thus, iron depletion may develop and then erythrocyte zinc protoporphyrin (ZPP) is formed during the final step of heme synthesis. The aim of this report is to describe the levels of ZPP in a dog with absolute primary polycythemia submitted to serial phlebotomies. A female mongrel dog, 6 year old, 27.2 kg body weight, had been submitted to phlebotomies, once or twice monthly for 3 years. A volume of 500 mL of total blood had been removed each time, and that procedure may have caused iron loss. After that 3 years period, ZPP has started being evaluated, for 6 times, during 4 months. Blood samples were collected in EDTA tubes and ZPP was determined by hematofluorometry method (ProtoFluor®Z--Helena Laboratories). ZPP values were obtained three times/ sample until 6 hrs after blood collection. On the first measurement, a high level of ZPP (194.66 μmol ZPP/mol heme) was observed (unpublished data--ZPP in normal dogs 62.33±4.52 [mean±SEM]). Then, iron supplementation started (250 mg/day of ferrous sulphate), and a progressive decrease of ZPP was noticed (from 194.66 to 110.33 μmol ZPP/mol heme) resulting in decrease of 43.3%. The initial high value of ZPP may suggest depletion of iron, probably in consequence of frequent past phlebotomies. After iron supplementation, the production of ZPP was reduced but still not reaching normal levels, suggesting that a degree of iron depletion was still remained. Data of ZPP observed may be considered as an important diagnostic indicator of iron deficiency in consequence of serial blood withdrawals. However, more studies correlating ZPP, serum iron and ferritin are necessary to investigate the clinical use of erythrocyte ZPP determination.