Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Primary Hyperparathyroidism ?
    ### Response:
    High PTH levels trigger the bones to release increased amounts of calcium into the blood, causing blood calcium levels to rise above normal. The loss of calcium from bones may weaken the bones. Also, the small intestine may absorb more calcium from food, adding to the excess calcium in the blood.
    