Telomere tests measure the length of telomeres, which are the protective caps at the ends of chromosomes. These caps shorten as cells age, so telomere length is considered a potential marker of biological age. Telomere tests measure the length of telomeres, which are the protective caps at the ends of chromosomes. These caps shorten as cells age, so telomere length is considered a potential marker of biological age. Health and Fitness, Health Tips, Exercises & Workout Tips, Diet & Wellness | Times of India Lifestyle