Serum Copper and Neutropenia in Elite Sailors

Abstract

PURPOSE: Haematological and biochemical monitoring of an Olympic Sailing Squad was undertaken through the Beijing Olympic cycle. One aspect of this was the investigation of serum copper deficiency as a cause of neutropenia in sailors. To the authors' knowledge, this relationship has not been investigated in elite athletes. Neutrophil function has been shown to be impaired in sedentary subjects with marginal and severe copper deficiency (Bonham et al 2002). METHODS: Seventeen males and 11 females comprising the Great Britain Olympic Sailing Team. Blood samples were collected between May 2007 and November 2008; between three and on a maximum of ten occasions as part of haematological and biochemical profiling. Sampling frequency was determined by sailor availability in the U.K., and health concerns and performance. Sailors were sub-divided into a neutropenic (N) group (neutrophil count of ≤1.5) and a non-neutropenic (NN) group (neutrophil counts always ≥1.7). Samples were drawn, fasted, between 8-10 am, and 36-48 hours post training. Blood was collected for haematological analysis in K3 EDTA tubes. Serum copper was drawn into specialised trace element K2EDTA tubes. Routine and serum copper analyses were undertaken at a clinical laboratory. Serum copper (μmol/L) reflects copper status (Harvey et al 2009). Data are represented as mean (SD). The mean copper value between the N and NN groups was compared using an unequal variance unpaired t-test. RESULTS: Over 17 months a total of 28 sailors were sampled, comprising 168 blood samples. This period included the lead into Beijing Olympic Games, and post Games, and the entire Olympic Sailing Squad. The neutrophil count for the whole squad was 2.9± 0.8×103/mm3:- N 1.8 ±0.4×103/mm3; NN 3.2 ±0.6×103/mm3. Serum copper concentration for the entire squad ranged from 10.5 to 22.1μmol/L, with a mean concentration of 15.1 ±1.9 μmol/L. Serum copper for the N and NN groups, was 13.8 ±1.2 μmol/L and 15.4 ±2.0 μmol/L respectively. There was a significant difference in serum copper concentration between the N and NN groups (p<0.05). CONCLUSIONS: Sailors prone to neutropenia had lower serum copper concentrations than the non-neutropenic sailors. Low serum copper may be a cause of impaired immune function in elite athletes.