A diagnostic assay strip includes a first layer that includes an iron mobile labelled specific binding partner that will bind to and iron biomarker from a sample and produce an iron complex and a vitamin A mobile labelled specific binding partner that will bind to a vitamin A biomarker from the sample and produce a vitamin A complex. A second layer includes iron and vitamin A test regions, and a control region. The iron test region has immobilized specific binding partners that will bind to the iron complex. The vitamin A test region has immobilized vitamin A biomarker that will bind to vitamin A mobile labelled specific binding partner, which is not bound to the vitamin A biomarker, passing from the first layer to the second layer. The control region has a moiety which will non-specifically bind to and immobilize the iron and vitamin A labelled specific binding partners. Methods of using the diagnostic assay strip are also discussed.