Definitions for the levels of evidence (I–IV) can be found at the end of the "Major Recommendations" field.
Guidelines
Agents containing aluminium should be used with caution in predialysis patients. (Level II evidence)
Suggestions for Clinical Care
(Suggestions are based on Level III and IV evidence)
- The recommended daily allowances for the general population should be used as a basis for the chronic kidney disease (CKD) population subgroup. Aluminium, copper, zinc, and selenium are special cases. (Opinion)
Copper
Deficiency does not appear to occur in renal failure. Copper may accumulate in CKD but it rarely increases to levels that are problematic. Apart from the situation of symptoms or signs suggestive of copper overload, and laboratory test confirmation in a particular patient, there is inadequate evidence to recommend routine measurement of copper in CKD patients.
Zinc
Zinc is one of the most important trace elements and is a component of many metabolic metalloenzymes. Zinc levels fall in CKD; the cause of the low levels has not been clarified. Dietary protein is a major source of zinc and limited protein intake due to low-protein diets or the anorexia of CKD may contribute to a low zinc level. Apart from the situation of symptoms or signs suggestive of zinc deficiency, and laboratory test confirmation in a particular patient, there is inadequate evidence to recommend routine measurement or dietary supplementation with zinc in those with CKD. The regular monitoring of serum zinc levels in patients with CKD who are following a protein-restricted diet is recommended.
Selenium
Similar to zinc, proteins are a rich source of selenium. Diets can be deficient in selenium in areas where the natural supply (in soils) of selenium is poor (e.g., New Zealand). Deficiency in selenium may be associated with cardiovascular disease, skeletal muscle myopathy, anaemia and problems with immune function. Selenium is renally excreted, but it is unknown how much selenium accumulates in CKD.
Selenium has a small therapeutic window. Selenium toxicity occurs when the soils are rich in selenium (e.g., some parts of the United States), when excess oral intake from naturopathy therapies has occurred, or from hyperalimentation.
Apart from the situation of symptoms or signs suggestive of selenium deficiency, and laboratory test confirmation in a particular patient, there is inadequate evidence to recommend routine measurement or dietary supplementation with selenium in CKD.
Regular monitoring of serum selenium levels in patients with CKD who are following a protein-restricted diet, especially in New Zealand, is recommended.
Aluminium
Aluminium clearance is reduced in renal failure. Aluminium absorption from the gastrointestinal tract can be enhanced in the presence of citrate, and so citrate-containing agents (e.g., sodium citrate) should be avoided in patients concurrently being administered aluminium-containing phosphate binders. Apart from the situation of symptoms or signs suggestive of aluminium overload and laboratory test confirmation in a particular patient, or patients on aluminium phosphate binders, there is inadequate evidence to recommend routine measurement of aluminium in patients with CKD.
Other Trace Elements/Minerals
Elevated serum levels of chromium, lead, silicon, strontium, tin, and vanadium, and reduced serum levels of nickel and rubidium have been observed in CKD patients. The clinical significance of this is not known.
Definitions:
Levels of Evidence
Level I: Evidence obtained from a systematic review of all relevant randomized controlled trials (RCTs)
Level II: Evidence obtained from at least one properly designed RCT
Level III: Evidence obtained from well-designed pseudo-randomized controlled trials (alternate allocation or some other method); comparative studies with concurrent controls and allocation not randomized, cohort studies, case-control studies, interrupted time series with a control group; comparative studies with historical control, two or more single arm studies, interrupted time series without a parallel control group
Level IV: Evidence obtained from case series, either post-test or pretest/post-test
