Pitfalls in interpreting red blood cell parameters in elite high-altitude and sea-level athletes: A unique case series.

A Mireille Baart,Michiel G J Balvers,Jacqueline M T Klein Gunnewiek,Johannes Zwerver,Peter C J Vergouwen

doi:10.14814/phy2.14891

A Mireille Baart, Michiel G J Balvers + Show 3 more

Open Access

https://doi.org/10.14814/phy2.14891

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Abstract

Standard routine hematological measurements are commonly used to investigate differences in blood parameters between high‐altitude athletes (HAA) and sea‐level athletes (SLA), and to monitor the effect of high‐altitude training. In this way, red blood cell (RBC) parameters are usually expressed as relative parameters (concentration) rather than absolute parameters (total amount). In this unique case series of elite HAA and SLA, we describe how different ways of parameter expression can affect the interpretation of blood tests. In a group of 42 elite athletes, relative and absolute RBC parameters were compared between HAA and SLA. Absolute parameters were calculated by multiplying relative values with formula‐based estimated blood volume (BV‐e). Additionally, in two individual athletes, one HAA and one SLA, absolute parameters were also calculated with blood volume (BV) obtained by measurement with a dilution method (BV‐m). In men, HAA had a significantly higher hemoglobin (Hb) concentration (+7.8%; p = 0.001) and total Hb mass per kg body weight (BW) (+12.0%; p = 0.002). When not corrected for BW, HAA had a lower, non‐significant, total Hb mass (−7.8%; p = 0.055). In women, no significant differences between HLA and SLA were observed. The two individual athletes showed that, based on BV‐m, in the HAA, total Hb mass and total Hb mass per kg BW were respectively 14.1% and 31.0% higher than in the SLA, whereas based on BV‐e, in the HAA, total Hb mass was 20.8% lower and total Hb mass per kg BW was only 2.4% higher. Similar inconsistencies were observed for total RBC count. Thus, different ways of parameter expression, and different methods of BV assessment for the calculation of absolute parameter values, influence the interpretation of blood tests in athletes, which may lead to misinterpretation and incorrect conclusions.

Highlights

In the last decades, East African athletes, who are born and raised at high altitude, have dominated in middle-and long- distance running (Knechtle et al, 2016)
red blood cell (RBC) parameters are usually expressed as relative parameters rather than absolute parameters
high-altitude athletes (HAA) had a significantly higher Ht (+10.4%; p = 0.003), [Hb] (+7.8%; p = 0.001) and [RBC] (+10.7%; p = 0.004), and a significantly higher total Hb mass per kg body weight (BW) (+12.0%; p = 0.002) and total RBC count per kg BW (+11.9%; p = 0.006) compared to sea-level athletes (SLA)

Summary

| INTRODUCTION

East African athletes, who are born and raised at high altitude, have dominated in middle-and long- distance running (Knechtle et al, 2016) One explanation for their success is related to favorable hypoxia-induced hematological adaptations, among which an increase in red blood cell (RBC) mass, and an increase in oxygen transport capacity (Sinex & Chapman, 2015). The SLA was a 21-year-old male middle- distance runner, born and living in the Netherlands at sea level, who performed at European top ten level. He had not performed training at high altitude within 3 months before the measurements. Written informed consent was obtained from all the athletes prior to the analyses for this study

| METHODS

| RESULTS

| DISCUSSION

| Strengths and limitations