Table 5.
| Study | Year | Study type (Sample origin) | Demographics (AA cases)† | Sample Size Total (Detail) | Measures and outcomes |
|---|---|---|---|---|---|
| Yousefi et al.[78] | 2014 | Case- control (Hospital- based) | Sex: 12M/17F Age: 24.79 ± 11.93 Country: Iran |
61 (29 AA cases and 32 sex- and age-matched healthy controls recruited amongst patients’ family members) | RBC folate (median ng/mL/cells (range): AA 167.5 (52.5– 500) vs. controls: 285.5 (97.5–662) (P < 0.0001); Negative correlation between SALT score and RBC folate levels (r = −0.41, P = 0.03) |
| Ertugrul et al.[79] | 2013 | Case- control (Hospital- based) | Sex: 46M/29F Age: 29.2 ± 12.5 Country: Turkey |
129 (75 AA cases and 54 controls who had no dermatologic or systemic disease history) | No difference in serum folic acid, vitamin B12, homocysteine, or holotranscobalamin levels in AA vs. controls |
| Gonul et al.[72] | 2009 | Case- control (Not described) | Sex: 29M/14F Age: 29.1 ± 13.4 Country: Turkey |
79 (43 AA cases and 36 healthy sex and age-matched controls) | No difference in serum folate or vitamin B12 in AA vs. controls |
| Kalkan et al.[80] | 2013 | Case- control (Hospital- based) | Sex: 78M/58F Age: 32.27 ± 9.525 |
266 (136 AA cases and 130 age- and gender-matched controls) | Greater prevalence of MTHFR C677T polymorphisms (CT/TT vs. CC genotype) amongst AA vs. controls (P < 0.05) Serum Vitamin B12 (pg/mL): CT/TT: 276.28 ± 99.761 vs. CC: 283.94 ± 135.795 (P = 0.748) Serum folate (ng/mL): CT/TT: 8.36 ± 2.442 vs. CC: 7.76 ± 2.146 (P = 0.198 |
| Zafad et al.[81] | 2007 | Case-report | Sex: 1M Age: 24 Country: Morocco |
1 AA | Patient diagnosed with pernicious anemia associated with hemolytic anemia at age 16 and developed AA at age 24 |
| Tzellos et al. [73] | 2009 | Case-report | Sex: 1M Age: 18 Country: Greece |
1 AA | Low serum vitamin B12 (76.8 pg/ml, reference 240–900 pg/mL); normal folate levels |
AA alopecia areata, CI confidence interval, OR odds ratio, RBC red blood cell, SALT severity of alopecia tool
*
Normal serum vitamin B12 range 240–900 pg/ml
†
Age given as mean ± standard deviation