You high heart rate (tachicardia) was confirmed by the ECG. Doctor ordered these laboratory tests to estimate your general health condition and to find out if there is some reason outside the heart that causes tachicardia in your case.
Blood glucose level is the major indicator for diagnosing diabetes or hypoglycemia.
Thyroid stimulant hormone (TSH) and thyroxine (T4) are used to evaluate the function of the thyroid gland. Many thyroid disorders can have impact on heart rate.
Complete blood count (CBC) can give us information if you have some infection or anemia or can give us directions for further examinations.
Ferritin is blood marker used to estimate the iron reserves in the body. Low ferritin is indicator for iron deficit anemia than can also cause tachicardia.