Hemoboost is a registered natural product containing specially processed haemolysed haemoglobin and iron dextran. It is marketed for human use on the basis of many years' use and documented effect in veterinary medicine. Iron dextran was introduced for use in human medicine in 1954.

Krauterblut is a registered natural product made from a number of herbs where the active substance is ferrous gluconate. Both drugs have been available for a number of years and have become increasingly popular among patients and healthcare staff due to a reduction in adverse effects.

The objective of this study is to determine the effect and adverse effects of the natural products Hemoboost and Kräuterblut compared with the usually administered ferrous sulphate in knee arthroplasty.

Hip and knee arthroplasties are performed with increasing frequency in the western world, and in Denmark approximately 12,000 operations are performed annually (2/1000/year). The perioperative and postoperative blood loss generally constitutes ½ -1½ litres which is frequently associated with symptom-producing anaemia which obstructs mobilisation and increases the risk of complications.

Postoperative iron supplementation for a period of up to 12 weeks is therefore a frequently adopted practice. However, there is no consensus or evidence that support postoperative iron supplementation and the effects of iron deficiency are unclear. It is well-known that iron supplementation causes gastrointestinal adverse effects in up to 25% of cases.

Inclusion Criteria:

• age > 18 years
• ASA group I-II

Exclusion Criteria:

• malignant disorder
• chronic renal insufficiency
• urinary tract infection
• haemorrhagic diathesis
• haemoglobin < 7 mmol/l
• dementia or mental disorder incompatible with survey participation