Challenges in the Measurement and Interpretation of Serum Titanium Concentrations

The measurement of circulating metal ion levels in total hip arthroplasty patients continues to be an area of clinical interest. National regulatory agencies have recommended measurement of circulating cobalt and chromium concentrations in metal-on-metal bearing symptomatic total hip arthroplasty patients. However, the clinical utility of serum titanium (Ti) measurements is less understood due to wide variations in reported values and methodology. Fine-scale instrumentation for detecting in situ Ti levels continues to improve and has transitioned from graphite furnace atomic absorption spectroscopy to inductively coupled plasma optical emission spectrometry or inductively coupled plasma mass spectrometry. Additionally, analytical interferences, variable sample types, and non-standardized sample collection methods complicate Ti measurement and underlie the wide variation in reported levels. Normal reference ranges and pathologic ranges for Ti levels remain to be established quantitatively. However, before these ranges can be recognized and implemented, methodological standardization is necessary. This paper aims to provide background and recommendations regarding the complexities of measurement and interpretation of circulating Ti levels in total hip arthroplasty patients.