# A long-lasting low oxygen saturation hiding Titusville hemoglobin diagnosis in a premature 14-month-old child – case report

## TL;DR

A 14-month-old child with a rare hemoglobin variant, Hb Titusville, showed misleading low oxygen saturation readings despite normal blood oxygen levels and good health.

## Contribution

This case highlights the diagnostic challenge of Hb Titusville, a rare hemoglobinopathy causing unexplained low SpO2.

## Key findings

- The child had normal PaO2 and clinical condition despite persistently low SpO2 after recovery.
- Hb Titusville was diagnosed using high-performance liquid chromatography and molecular analysis.
- The case underscores the need for systematic evaluation to avoid misdiagnosis in similar clinical scenarios.

## Abstract

There are some clinical conditions that can impact the accuracy of spO2 measurements, leading to an incorrect diagnosis of hypoxemia. Low oxygen affinity hemoglobinopathy can present with low spO2 and discordance with PaO2 and general clinical conditions.

We report the case of a 14-month-old male, born extremely premature, with severe bronchopulmonary dysplasia (BPD). He required continuous high-flow nasal cannula (HFNC) oxygen therapy and was hospitalized due to a viral respiratory infection causing dyspnea and desaturation. Once the child clinically recovered, all attempts to wean him off oxygen resulted in rapid drops in SpO2. This occurred despite the absence of increased work of breathing, cyanosis, or abnormal PaO2.

Severe BPD and recurrent respiratory issues could have per se justified the persistently low spO2. Incongruence between low spO2 values, normal PaO2 levels and good clinical condition, once the child was recovered, raised suspicion of low oxygen affinity hemoglobin (Hb) variants. Abnormal Hb peak detected through high-performance liquid chromatography allowed rare diagnosis of Hb Titusville, confirmed by molecular analysis. In conclusion, the case matched a rare low oxygen affinity hemoglobinopathy (Hb Titusville), highlighting its relevance in unexplained hypoxemia. Diagnosis challenges necessitate a systematic approach to prevent misinterpretations.