Amongst the most frequently ordered nutritional tests in Australia are serum ferritin and serum vitamin B 12 . Both are very sensitive to deficiency states, but serum ferritin can be falsely normal in patients with iron deficiency who have coexisting infection or inflammatory disorders. Red cell B 12 is available but is rarely used. Red cell folate, on the other hand, is a useful addition to serum folate testing where there is a possibility of coexistant B 12 deficiency, for example in the elderly psychogeriatric patient on anticonvulsants. Of these, SGOT reactivation has proved of limited clinical use as it is hard to interpret clinically.
Some nutrients are particularly hard to test for.
Zinc is one of the most important examples. Hair analysis has been used to test for zinc and for toxic levels of heavy metal elements such as cadmium and mercury. However at present this method is susceptible to external interference and is not yet reliable enough for routine clinical use. Practice tips Where possible, assess function as well as nutrient concentration. Find out what supplements the patient is taking.