Nursing / General Practice / Primary Health Care / Folic acid / Family Practice / Humans / Female / Male / Aged / Middle Aged / Adult / Public health systems and services research / Retrospective Studies / Sensitivity and Specificity / Erythrocytes / Hemoglobins / Creatinine / vitamin B deficiency / Humans / Female / Male / Aged / Middle Aged / Adult / Public health systems and services research / Retrospective Studies / Sensitivity and Specificity / Erythrocytes / Hemoglobins / Creatinine / vitamin B deficiency