Valberg 1978.

Study characteristics
Patient Sampling	8 patients with clinically manifest primary haemochromatosis, 12 patients with cirrhosis and iron overload, and 20 patients with liver disease and low or normal iron stores. 34 healthy volunteers were added to establish a normal range of values for serum ferritin.
Patient characteristics and setting	A sample of 40 adult Canadian patients aged from 21 to 74 years old was selected. They were divided in 3 groups: Group A: 8 haemochromatosis ‐ 4 of whom were cirrhotic. Group B: 12 cirrhosis, composed by 6 alcoholic, 4 cryptogenic, 1 sideroblastic, and 1 porphyria. Group C: 20 normal or low iron on biopsy, composed by 2 fatty liver, 16 alcoholic cirrhosis, and 2 cryptogenic cirrhosis. There were 34 healthy volunteers aged from 17 to 38 years old too.
Index tests	Serum ferritin by two‐site radioimmunoassay with Luxton 1977 method. An elevated serum ferritin concentration (both sexes > 300 µg/L) was classified as iron overload.
Target condition and reference standard(s)	Liver iron content reporting method: liver biopsy sections were stained for hemosiderin with Prussian blue and coded. Grading was at follows: 0 = no iron; 1+ = iron in occasional cells; 2+ = iron in fewer than 50% of the cells; 3+ = iron in more than 50% of the cells; and 4+ = iron in all the cells in massive amounts. In accordance with the experience of Barry 1974: grades of 0 to 2+ were considered as indicating low to normal hepatic iron stores and grades of 3+ to 4+ as indicating excessive hepatic iron.
Flow and timing	Haematological tests for measuring iron status (serum‐iron concentration, transferrin saturation, SGOT index, and serum ferritin), and liver biopsy. The flow and timing of these two types of tests were not described.
Comparative
Notes	The mean serum ferritin concentration was 2221 µg/L in the patients with primary haemochromatosis or cirrhosis with excessive hepatic iron, but only 264 µg/L in patients with liver disease and low to normal hepatic iron stores. In the first two groups, all the individual values were greater than 300 µg/L, but in the third group only 8 of the 20 patients had values greater than 300 µg/L. A comparable separation of the healthy controls from the patients with primary haemochromatosis was obtained when iron absorption was plotted against the serum ferritin.
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	No
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		Low risk