Focusing on the laboratory diagnosis of sideroblastic anemia, the following table summarizes findings associated with inherited forms.
Table 10. Laboratory Findings in Select Inherited Porphyria.6 | Congenital Erythropoietic Porphyria (CEP) | Erythropoietic Protoporphyria (EPP) | X-Linked Erythropoietic Protoporphyria (XLEPP) |
| Affected Enzyme | Uroporphyrinogen III synthase deficiency | Ferrochelatase deficiency | ALA-synthase 2 (gain of function) |
| Affected Gene | UROS | FECH | ALAS2 |
| Inheritance Pattern | Autosomal recessive | Autosomal recessive | X-linked dominant |
| RBC Protoporphyrin | Normal | Marked increase | Slight increase |
| RBC Uroporphyrin | Marked increase | Normal | Normal |
| RBC Coproporphyrin | Moderate increase | Normal | Normal |
| Urine Protoporphyrin | Normal | Normal | Normal |
| Urine Uroporphyrin | Marked increase | Normal | Normal |
| Urine Coproporphyrin | Moderate increase | Normal | Normal |
| Feces Protoporphyrin | Normal | Moderate increase | Normal or slight increase |
| Feces Coproporphyrin | Slight increase | Normal | Normal |
| Additional Tests | Marked decrease in Uroporphyrinogen III synthase activity | Moderate decrease in Ferrochelatase activity | Moderate increase in ALA-synthase activity Moderate increase in FEP/ZPP |
*Adapted from Rodak's Table 17.2, p. 274
6. Keohane, E. M., Otto, C.N., Walenga, J. M. (2016). Rodak's Hematology Clinical Principles and Applications. St. Louis., Elsevier, 6th Edition.
