TABLE 2.
Characteristics of included studies in the meta-analysis for iron concentration in blood and CSF.
| Study | Country | Unit |
Parkinson’s disease |
Controls |
Methods to determine iron levels | Food fasting | ||||||
| n | Sex (% male) | Mean Age (years) | Iron level (mean ± SD) | n | Sex (% male) | Mean Age (years) | Iron level (mean ± SD) | |||||
| Studies on serum | ||||||||||||
| Cabrera-Valdivia et al., 1994 | Spain | μg/dL | 68 | 47.06 | 65.8 ± 0.96 | 82.7 ± 37.33 | 68 | 52.94 | 65.80 ± 1.00 | 70.9 ± 29.89 | – | yes |
| Logroscino et al., 1997 | America | μg/dL | 104 | – | – | 28.3 ± 11.6 | 352 | – | – | 33.9 ± 15.2 | AAGFM | – |
| Jimenez-Jimenez et al., 1998 | Spain | mg/L | 37 | 37.84 | 65.70 ± 8.80 | 1.01 ± 0.33 | 37 | 43.24 | 62.40 ± 17.8 | 0.95 ± 0.3 | AAS | yes |
| Forte et al., 2004 | Italy | μg/L | 26 | 92.31 | 64.90 ± 10.80 | 23.54 ± 8.59 | 13 | 46.15 | 63.80 ± 13.70 | 20.29 ± 7.02 | ICP-AES | yes |
| Forte et al., 2005 | Italy | ng/mL | 71 | 74.65 | 65.50 ± 9.40 | 1122 ± 432 | 44 | 75.00 | 51.90 ± 4.00 | 1596 ± 442 | ICP-AES | – |
| Hegde et al., 2004 | India | μol/mL | 27 | 51.85 | 57.15 ± 5.20 | 0.02 ± 0.004 | 25 | 52.00 | 55.40 ± 6.40 | 0.023 ± 0.009 | ICP-AES | – |
| Qureshi et al., 2006 | Sweden | mg/L | 19 | 32.00 | 72.00 ± 17.00 | 1.09 ± 0.45 | 21 | 38.09 | 62.00 ± 11.00 | 1.16 ± 0.23 | AAS | yes |
| Gellein et al., 2008 | Norway | μg/L | 38 | 48.48 | – | 1251 ± 551 | 99 | 48.48 | – | 1146 ± 463 | ICP-MS | – |
| Ahmed and Santosh, 2010 | India | μg/dL | 45 | 57.78 | 57.62 ± 9.10 | 110.4 ± 0.6 | 42 | 59.52 | 55.62 ± 3.25 | 123 ± 8 | ICP-AES | – |
| Fukushima et al., 2010 | China | μg/mL | 58 | 62.00 | 64.20 ± 9.40 | 2 ± 0.83 | 82 | 57.31 | 63.65 ± 9.35 | 1.5 ± 0.78 | ICP-AES | yes |
| Madenci et al., 2012 | Turkey | μg/dL | 60 | 55.00 | 68.50 ± 8.30 | 74.6 ± 29.29 | 42 | 52.38 | 66.90 ± 8.30 | 74.8 ± 27.11 | – | yes |
| Farhoudi et al., 2012 | Iran | mg/dL | 50 | 56.00 | 64.53 ± 10.18 | 70.22 ± 25.18 | 50 | 50.00 | 63.53 ± 9.78 | 67.62 ± 39.53 | Biochemical methods | no |
| Fukushima et al., 2013 | China | μg/mL | 58 | 62.00 | 64.30 ± 9.40 | 2.1 ± 0.84 | 81 | 58.02 | 63.70 ± 9.40 | 1.51 ± 0.78 | ICP-AES | yes |
| Hu et al., 2015 | China | nmol/mL | 102 | 46.09 | 56.31 ± 13.38 | 4.12 ± 1.06 | 31 | – | – | 4.19 ± 1.05 | ELISA | yes |
| Mariani et al., 2016 | Italy | ug/dL | 92 | 67.40 | 70(38–83) | 79 ± 34 | 112 | 35.80 | 62(31–87) | 86.1 ± 34.9 | American Monitor KDA analyzer | yes |
| Sanyal et al., 2016 | India | μg/L | 250 | 64.80 | 57.88 ± 12.06 | 1156 ± 264.94 | 280 | 65.35 | 56.42 ± 9.68 | 1205.49 ± 316.09 | AAS | no |
| Studies on plasm | ||||||||||||
| Zhao et al., 2013 | China | μg/L | 238 | 50.80 | 67.10 ± 11.30 | 1656 ± 749 | 153 | 50.66 | 67.00 ± 12.10 | 1470 ± 648 | AAS | yes |
| Kumudini et al., 2014 | India | ng/mL | 150 | 71.33 | 55.70 ± 10.60 | 554.4 ± 123.8 | 170 | 70.58 | 53.73 ± 10.90 | 421.7 ± 126.1 | ICP-AES | – |
| Studies on CSF | ||||||||||||
| Gazzaniga et al., 1992 | Italy | μg/L | 11 | 90.91 | 64.9(49–78) | 181 ± 75.1 | 22 | 90.90 | – | 275.9 ± 153.6 | AAS | – |
| Jimenez-Jimenez et al., 1998 | Spain | mg/L | 37 | 37.84 | 65.70 ± 8.80 | 0.17 ± 0.17 | 37 | 43.24 | 62.40 ± 17.80 | 0.21 ± 0.15 | AAS | yes |
| Forte et al., 2004 | Italy | μg/L | 26 | 92.31 | 64.90 ± 10.80 | 33 ± 29.4 | 13 | 46.15 | 63.80 ± 13.70 | 73.3 ± 72.7 | ICP-AES | yes |
| Qureshi et al., 2006 | Sweden | μg/L | 19 | 68.42 | 72.00 ± 17.00 | 397 ± 217.94 | 21 | 38.09 | 62.00 ± 11.00 | 237 ± 169.56 | AAS | yes |
| Bocca et al., 2006 | Italy | ng/mL | 91 | 70.33 | 65.50 ± 9.70 | 28.2 ± 14.6 | 18 | 55.56 | 63.30 ± 13.80 | 45 ± 30.2 | ICP-AES | yes |
| Alimonti et al., 2007a | Italy | μg/L | 42 | 85.71 | 64.50 ± 10.70 | 28.2 ± 14.6 | 20 | 85.00 | 66.20 ± 14.70 | 35.5 ± 5.03 | ICP-AES | yes |
| Hozumi et al., 2011 | Japan | μg/L | 20 | 45.00 | 68.7 ± 5.8 | 263.9 ± 112.9 | 15 | 40.00 | 48.2 ± 22.2 | 238 ± 54.7 | ICP-MS | – |
| Hu et al., 2015 | China | nmol/mL | 51 | 45.10 | 61.23 ± 13.18 | 0.458 ± 0.197 | 31 | – | – | 0.495 ± 0.173 | ELISA | yes |
| Sanyal et al., 2016 | China | μg/L | 50 | 70.00 | 58.72 ± 12.83 | 182.88 ± 89.28 | 60 | 70.00 | 60.11 ± 10.44 | 212.46 ± 33.58 | AAS | no |
AAS, Atomic absorption spectrophotometer; AAGFM, Atomic absorption graphite furnace micromethod; ELISA, Enzyme linked immunosorbent assay; ICP-AES, Inductively coupled plasma atomic emission spectrometry; ICP-MS, Inductive coupled plasma mass spectroscopy.