A patient with a parathormone (PTH) level of 6pg/mL. What oberservations should a nurse relate to this result when looking at electrocardiogram?

Depends. low PTH can be primary or secondary thus hypercalcemia or hypocalcemia. Hypocalcemia causes QT prolongation or prolonged ST segment. Hypercalcemia causes shortened QT interval. I guess the first step is to know what is going with the calcium level so you can look for the appropriate changes on EKG.