Table 1.

Aetiology of copper deficiency

Primary cause	Number of cases (%)	Potential additional causes (number of cases)	References
Previous upper gastrointestinal surgery	26 (47%)
Non-bariatric	17	Mesangioproliferative glomerulonephritis with high urinary copper levels (1) [2], small intestine bacterial overgrowth and denture cream use with normal serum zinc levels (1) [74]	[2, 4, 12, 13, 28, 38, 39, 41, 44, 47, 63, 74, 77, 88]
Bariatric	9	Zinc supplement use with normal serum zinc levels (1) [38, 39]	[16, 29, 38, 39, 44, 47]
Zinc overload	9 (16%)
Denture cream	4		[58]
Supplements	2		[38, 44, 45, 67]
Haemodialysis	1		[89]
Unknown	2	Coeliac disease well-controlled on gluten-free diet (1) [19]	[19, 24]
Malabsorption	8 (15%)
Coeliac disease	4		[21, 38, 44, 46]
Unknown	4		[30, 38, 44]
Iron supplements	1 (2%)		[38, 41, 44]
Idiopathic	11 (20%)	High serum zinc levels without reported cause (7) [18, 38, 39, 41, 42, 44]	[1, 18, 38, 39, 41, 42, 44]

Cases are classified according to the reported primary cause. Any potential additional causes are also listed