In the present work, a case-control study was performed to assess if the risk to develop HT and GD is associated with the promoter single nucleotide polymorphisms (SNPs) IL1B-511 C/T (rs16944), TNFA-308 G/A (rs1800629), IL6-174 G/C (rs1800795), and IFNGR1-56 T/C (rs2234711). This evidence concerns the gene IL6 and hematocrit.