The primary role of parathormone, or parathyroid hormone (PTH), is to control calcium levels in the blood. PTH also plays a role in regulating phosphorus and vitamin D levels.
Detailed Explanation of Parathormone's Role
Here's a more in-depth breakdown of PTH's function:
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Calcium Regulation: PTH is crucial for maintaining a normal concentration of calcium in the blood. When blood calcium levels drop too low, the parathyroid glands release PTH. This triggers several actions:
- Bone Resorption: PTH stimulates the release of calcium from bones into the bloodstream.
- Kidney Reabsorption: PTH increases calcium reabsorption in the kidneys, preventing it from being lost in the urine.
- Vitamin D Activation: PTH promotes the activation of vitamin D in the kidneys, which then enhances calcium absorption from the intestine.
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Phosphorus Regulation: PTH also influences phosphorus levels, generally lowering them. It does this by:
- Increasing Kidney Excretion: PTH increases the excretion of phosphorus by the kidneys.
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Vitamin D Regulation: As mentioned earlier, PTH indirectly regulates vitamin D by activating it in the kidneys. Active vitamin D (calcitriol) plays a crucial role in calcium absorption from the diet.
Consequences of Abnormal PTH Levels
According to the reference provided, having too much or too little parathyroid hormone can lead to symptoms related to abnormal blood calcium levels. This can manifest as:
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Hyperparathyroidism (Too much PTH): This can lead to hypercalcemia (high blood calcium), which can cause:
- Bone pain
- Kidney stones
- Excessive urination
- Muscle weakness
- Fatigue
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Hypoparathyroidism (Too little PTH): This can lead to hypocalcemia (low blood calcium), which can cause:
- Muscle cramps
- Numbness and tingling in the fingers and toes
- Seizures
