# Laboratory reference intervals influence referral patterns for hemoglobin abnormalities in the Ontario virtual care system

## TL;DR

Lab reference ranges for hemoglobin affect how often doctors refer patients for specialist advice in Ontario’s virtual care system.

## Contribution

The study shows lab-specific hemoglobin thresholds influence eConsult referral patterns and proposes a standardized anemia management algorithm.

## Key findings

- Referrals for anemia in females varied by 7.5 g/L depending on lab reference intervals.
- Most eConsults lacked key pre-referral tests like ferritin, B12, and reticulocyte count.
- Standardized hemoglobin thresholds and pre-referral testing could reduce unnecessary referrals.

## Abstract

This retrospective cross-sectional study investigates the impact of laboratory-specific hemoglobin reference intervals on electronic consultation (eConsult) referral patterns for suspected anemia and elevated hemoglobin at a tertiary care center in London, Ontario that serves Southwestern Ontario. The study analyzed referrals through the Ontario Telemedicine Network’s eConsult platform for hemoglobin abnormalities, excluding patients under 18 years old, between July 1, 2019, and June 30, 2023.The main outcome measures were influence of hemoglobin reference intervals on the referral patterns for suspected anemia and elevated hemoglobin, as well as the extent of pre-referral laboratory testing. Of the 619 eConsults reviewed, 251 referrals for suspected anemia and 93 for elevated hemoglobin were analyzed. Referral patterns showed significant variance in hemoglobin levels based on different laboratory thresholds. Referrals for suspected anemia in females from laboratories whose lower limit was 120 g/L or greater had a hemoglobin concentration 7.5 g/L greater than referrals that used laboratories with a threshold lower than 120 g/L. The study also identified potential areas for improvement in pre-referral investigations; 44% of eConsults did not provide a ferritin level, 53% were missing a B12 level, and 81% were missing a reticulocyte count. In conclusion, laboratory reference intervals for hemoglobin significantly influence referral patterns for suspected hemoglobin abnormalities in Ontario’s eConsult system. There is a need for standardized reference intervals and comprehensive pre-referral testing to avoid unnecessary medicalization and referrals. We propose an anemia management algorithm to guide primary care providers in the pre-referral investigation process.

Changes in hemoglobin levels, the proteins in red blood cells that carry oxygen around in the body, are common reasons for referrals. In Ontario, Canada, healthcare practitioners have access to electronic consults (eConsults) to ask for specialist advice for various conditions, including suspected anemia (low hemoglobin) or erythrocytosis (high hemoglobin). However, what’s considered ’normal’, ‘high’, and ‘low’ hemoglobin levels can vary from one lab to another. Our research looked at how these differences affect physicians’ decisions to request an eConsult. We found that when labs set higher ’normal’ levels for hemoglobin, doctors were more likely to ask for a specialist opinion. We also noticed that many eConsults did not include all test results needed for an effective eConsult. We believe that having a common standard for hemoglobin intervals and making sure all necessary tests results are included could prevent unnecessary eConsults and lead to higher quality advice from specialists. To help with this, we’ve come up with a guide for doctors to use when deciding to send an eConsult, aiming to make care more efficient and convenient for patients.