Iron homeostasis and perioperative management of iron deficiency

Abstract

Describe the physiology of iron and its importance for mammalian health and function. Discuss which groups of patients require further investigation for iron deficiency anaemia, including those with normal serum ferritin values in whom a response to iron therapy is seen. Explain the rationale and pitfalls of laboratory tests in assessing iron status. Optimise iron status, particularly in patients scheduled for surgery. Iron is an essential bioelement in human physiology. It has key roles in cellular respiration: facilitating the formation of Adenosine triphosphate (ATP), oxygen transport through iron-containing haem groups (haemoglobin [Hb] and myoglobin), and protection against infection via iron withholding in the immune system. Iron excess results in toxicity, most notably to the heart and liver. Iron deficiency (ID) affects more than 2 billion people worldwide and remains the leading cause of anaemia. This review gives an overview of the physiology of iron metabolism and its impact on key groups of patients presenting for surgery, and summarises how to investigate and treat ID. Iron homeostasis The human body contains approximately 3e4 g iron in males and 2.5 g in females; 2.5e3.5 g of this in males is contained as Hb, 0.3e0.4 g as myoglobin, 100 mg as haem/non-haem Stuart Cleland BSc FRCA is a consultant in anaesthesia with clinical interests in upper gastrointestinal, hepatobiliary, and obstetric anaesthesia, and the preoperative assessment and optimisation of high-risk patients. He chairs his hospital's transfusion committee, and is the departmental lead for the management of perioperative anaemia. Wayne Thomas BSc (Hons) MRCP FRCPath is a consultant haematologist with a subspecialty interest in haemostasis, thrombosis, and iron deficiency. He is the laboratory lead for general haematology for his Trust, and clinical lead for blood transfusion. He is exchairman of the British Society of Haematology general haematology guidelines committee, and chairman of the UKNEGAS steering committee for haematology.

Observational study of pre‐operative intravenous iron given to anaemic patients before elective cardiac surgery

“…A high disease burden can cause chronic systemic inflammation, impacting on iron metabolism and homeostasis by upregulating hepcidin, the hormone responsible for controlling iron metabolism [12]. Hepcidin reduces, or prevents, dietary iron uptake and also inhibits, or prevents, release of stored iron for Hb synthesis; upregulation can lead to profound iron depletion and consequently functional iron deficiency anaemia [10,13].…”

“…FBC, full blood count; U&E, urea and electrolytes; CRP, c-reactive protein; TFT, thyroid function test; Hb, haemoglobin; i.v., intravenous; CKD, chronic kidney disease; GI; gastro-intestinal; MCV, mean corpuscular volume; MCH, mean corpuscular haemoglobin no statistically significant differences between pretreatment Hb and time between iron administration and surgery. Treatment-responsive patients had a mean (95%CI) increase in Hb after receiving iron of 17(13)(14)(15)(16)(17)(18)(19)(20)(21) g.l -1 (range 6-44 g.l -1 ) achieving mean (SD) pre-operative Hb of 137(8) g.l -1 , whereas the Hb of treatment-unresponsive patients p < 0.001) or untreated anaemic (rate ratio 2.27, 95%CI 1.43-3.80; p < 0.001) groups. Non-anaemic and treatmentresponsive patients were equally likely to avoid transfusion (p = 0.390).…”

Saponins and Tannin Levels in Chayote, Mung Beans, and Biscuits from Chayote and Mung Beans

“…The highest average yield of the saponin content was in the biscuits formulation (1:1), which is 4,315 g/100 g, and the lowest is on the mung beans-based biscuits which are 1,558 g/100 g Table 2. Saponins are polar compounds, because they have a number of hydroxyl groups and glycosides, meaning they are easily soluble in the solvent n-butanol [10]. The entire n-butanol solution was mixed and evaporated with a rotary evaporator until a concentrated extract was obtained.…”

“…As a result, there is a risk of experiencing iron deficiency. Iron is needed by the body for the formation of red blood cells [10], [11].…”

Hong Kong Society of Clinical Blood Management recommendations for implementation of patient blood management

“…At the University Hospitals Plymouth, UK, intravenous iron is given to successfully treat iron deficiency anaemia when surgery with anticipated blood loss of >500 mL is anticipated within 6 weeks. 32 As a result, intravenous iron has become an important component of PBM management strategies.…”