Table 4.

Previous studies on serum zinc, copper, selenium, and iron levels in patients from different countries diagnosed with different diseases.

	Country	Disease	Serum levels	p-value	Reference
Copper	Sweden	Sclerotic heart valves	1258 ± 412 ng/mL	p < 0.05	Nyström-Rosander et al.15
	Turkey	Rheumatic heart disease	1.93 ± 0.59 µg/L	p < 0.001	Kosar et al.38
	Turkey	Heart failure	880 ± 185 µg/L	0.000	Kosar et al.39
	Netherlands	Fatal cases of cardiovascular disease	1.32 ± 0.31 mg/L	p > 0.05	Kok et al.55
	Turkey	Aortic valve sclerosis	93.68 ± 27.21 µg/dL	p = 0.233	The present study
	Sweden	Sclerotic heart valves	1357 ± 481 ng/mL	p > 0.05	Nyström-Rosander et al.15
Iron	Poland	Heart failure	79 ± 44 μg/dL	–	Tkaczyszyn et al.43
	Turkey	Aortic valve sclerosis	58.17 ± 26.00 µg/dL	p = 0.059	The present study
	Sweden	Sclerotic heart valves	99.9 ± 13.8 ng/ml	p < 0.001	Nyström-Rosander et al.15
	Turkey	Rheumatic heart disease	136 ± 11 µg/l	p < 0.05	Kosar et al.38
Selenium	Finland	Coronary heart disease	51.8 ± 13.82 µg/L	–	Salonen et al.48
	Turkey	Heart failure	121 ± 5 µg/L	0.000	Kosar et al.39
	France	Cardiomyopathy	69 ± 2 µg/L	–	Auzepy et al.49
	Finland	Acute myocardial infarction	48 ± 12 µg/L	–	Westermarck47
	Turkey	Aortic valve sclerosis	60.85 ± 11.63 µg/L	p = 0.807	The present study
	Sweden	Sclerotic heart valves	752 ± 216 ng/mL	p < 0.05	Nyström-Rosander et al.15
	Turkey	Rheumatic heart disease	0.41 ± 0.16 µg/L	p < 0.001	Kosar et al.38
Zinc	Turkey	Heart failure	555 ± 104 µg/L	<0.01	Kosar et al.39
	Netherlands	Fatal cases of cardiovascular disease	0.71 ± 0.19 mg/L	p > 0.05	Kok et al.55
	Turkey	Aortic valve sclerosis	73.11 ± 10.52 µg/dL	p = 0.000	The present study

Concentrations are shown in their mean ± SD or median form.