Platelet Indices Analyzed for Tuberculosis and Diabetes Mellitus Co-Morbidity

Type 2 diabetes mellitus (DM) has been verified as one of the threatening risk factors for TB, and patients have three times the risk of developing TB compared to non-diabetic patients due to pathogenic mechanisms and metabolic factors.

Platelets are enucleate cells and have critical roles in thrombosis, homeostasis and the inflammatory response. When the internal environment is changed, platelet morphology may be altered and play a role in certain platelet-associated parameters, mainly including platelet count (PC), plateletcrit (PCT), platelet distribution width (PDW) and mean platelet volume (MPV).

Clinical Laboratorians at Nantong University College of Medicine (Nantong, China) enrolled in a study 246 patients admitted to the hospital and were distributed into three groups (113 TB, 59 DM and 74 TB + DM). A total of 133 individuals were also recruited as healthy controls (HC). Platelet indices, namely, platelet count (PC), mean platelet volume (MPV), plateletcrit (PCT) and platelet distribution width (PDW), were compared among the four groups, and the relationship with inflammatory markers was explored by using statistical software.

TB diagnose was based on positive results of Xpert MTB/RIF (Cepheid Inc., Sunnyvale, CA, USA). The team used BACTEC MGIT 960 rapid liquid isolate culture (Becton Dickinson, Sparks, MD, USA), and the GenoType check system (Hain Lifescience, Nehren, Germany), and MTB smear confirmation by Ziehl-Neelsen acid-fast stain. Full blood counts were carried out using Mindray BC-6800 hematology analyzer (Shenzhen Mindray Bio-Medical Electronics Co. Ltd., Shenzhen, China). The Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were also measured.

The scientists reported that MPV and PCT were significantly downregulated in TB + DM patients (9.95 ± 1.25 fL, 0.20 ± 0.05%, separately) compared with DM individuals (10.92 ± 1.17 fL, 0.22 ± 0.04%). Moreover, the changes in MPV were significantly higher in TB + DM patients (9.95 ± 1.25 fL) than in TB patients (9.42 ± 1.01 fL). MPV improved the diagnosis sensitivity when it was combined with clinical parameters, such as fasting blood glucose in DM and Mycobacterium tuberculosis culture result in TB (76.3% versus 64.9%, 72.6% versus 60.8%), respectively. In addition, the sensitivity and specificity of PCT in the differential diagnosis of DM patients versus TB + DM patients were 69.5 and 59.4%, respectively. PCT improved the diagnosis sensitivity when combined with fasting blood glucose in DM (72.9% versus 64.9%). In addition, MPV was linked to CRP and ESR in the TB + DM patients.

The authors concluded that MPV is a valuable candidate marker to screen for TB-DM coinfection risk, as the occurrence of TB developing into TB-DM coinfection will increase MPV levels, and DM developing into a DM-TB coinfection will decrease MPV levels. MPV has significant specificity and sensitivity for predicting and diagnosing DM-TB coinfection. The study was published on May 20, 2021 in the journal BMC Infectious Diseases.

Related Links:
Nantong University College of Medicine
Cepheid Inc
Becton Dickinson
Hain Lifescience
Shenzhen Mindray