Abstract

Increased levels of parathyroid hormone, whether in primary or secondary hyperparathyroidism, disrupt normal calcium metabolism, leading to bone demineralization, hypercalcemia, and associated clinical manifestations. Management of hyperparathyroidism typically involves addressing the underlying cause, surgical removal of abnormal parathyroid tissue (in primary hyperparathyroidism), and medications to regulate calcium and PTH levels

What happens when parathyroid hormone is increased?

When parathyroid hormone (PTH) levels are increased, a condition known as hyperparathyroidism occurs. Hyperparathyroidism can be classified into two main types: primary hyperparathyroidism and secondary hyperparathyroidism. Here’s what happens when PTH is increased in each type:

1. Primary Hyperparathyroidism:
   • Primary hyperparathyroidism occurs due to excessive secretion of PTH from the parathyroid glands, usually as a result of a benign tumor (adenoma) in one or more of the parathyroid glands.
   • Elevated levels of PTH lead to increased calcium reabsorption from the bones, resulting in bone resorption and loss of bone density. This can cause osteoporosis, bone pain, and an increased risk of fractures.
   • PTH also enhances the reabsorption of calcium from the kidneys, leading to hypercalcemia (elevated blood calcium levels). Hypercalcemia can cause symptoms such as fatigue, weakness, kidney stones, and gastrointestinal disturbances.
   • In primary hyperparathyroidism, the increased PTH secretion is not appropriately suppressed by calcium levels in the blood, leading to dysregulated calcium metabolism.
2. Secondary Hyperparathyroidism:
   • Secondary hyperparathyroidism occurs as a compensatory response to conditions that cause low calcium levels in the blood, such as chronic kidney disease (CKD) or vitamin D deficiency.
   • In secondary hyperparathyroidism, the parathyroid glands enlarge and produce excess PTH in an attempt to restore normal calcium levels. However, this compensatory mechanism often leads to hyperplasia (enlargement) of the parathyroid glands and persistent elevation of PTH levels.
   • The increased PTH levels in secondary hyperparathyroidism stimulate bone resorption, leading to bone loss and the development of osteoporosis. Additionally, PTH promotes renal calcium reabsorption, which can exacerbate hypercalcemia and contribute to the development of metastatic calcifications in soft tissues.
   • Secondary hyperparathyroidism is commonly seen in patients with advanced CKD, where impaired kidney function results in decreased activation of vitamin D and impaired calcium homeostasis.

In hyperparathyroidism, various blood tests may show abnormalities indicative of altered calcium and phosphorus metabolism. Additionally, hyperparathyroidism can affect the brain and lead to several serious complications. Here are the typical blood results in hyperparathyroidism and the effects of the condition on the brain:

1. Blood Results in Hyperparathyroidism:
   • Hypercalcemia: Serum calcium levels are elevated due to excessive release of parathyroid hormone (PTH), which promotes calcium mobilization from bones, increases renal calcium reabsorption, and enhances intestinal calcium absorption.
   • Hypophosphatemia: Blood phosphorus levels may be decreased as a result of increased renal excretion of phosphorus due to elevated PTH levels.
   • Elevated Serum Parathyroid Hormone (PTH): In primary hyperparathyroidism, serum PTH levels are typically elevated due to abnormal functioning of one or more parathyroid glands.
2. Effects of Hyperparathyroidism on the Brain:
   • Cognitive Dysfunction: Chronic hypercalcemia associated with hyperparathyroidism can impair cognitive function and lead to symptoms such as confusion, memory problems, difficulty concentrating, and mood changes. These cognitive symptoms may affect daily activities and quality of life.
   • Psychiatric Symptoms: Severe hypercalcemia can manifest with psychiatric symptoms, including depression, anxiety, agitation, hallucinations, and psychosis. These symptoms may require psychiatric evaluation and management.
   • Increased Risk of Cerebrovascular Events: Chronic hypercalcemia has been associated with an increased risk of cerebrovascular events such as stroke and transient ischemic attacks (TIAs). Elevated calcium levels can promote vascular calcification and endothelial dysfunction, contributing to cerebrovascular pathology.
   • Neurological Complications: In severe cases of hyperparathyroidism, particularly when accompanied by marked hypercalcemia, patients may experience neurological complications such as seizures, coma, and encephalopathy. These complications can occur due to direct effects of elevated calcium levels on neuronal function and cerebral blood flow regulation.
3. Most Serious Effect of Hyperparathyroidism:
   • Renal Complications: One of the most serious effects of hyperparathyroidism is its impact on renal function. Chronic hypercalcemia and hypercalciuria associated with hyperparathyroidism can lead to the development of kidney stones (nephrolithiasis) and nephrocalcinosis (calcium deposits in the kidneys). Over time, these renal complications can progress to chronic kidney disease (CKD) and renal failure if left untreated.

Hyperparathyroidism can have significant effects on various organ systems, including the brain. Prompt diagnosis and management of hyperparathyroidism are essential to prevent complications and improve patient outcomes. Treatment may involve surgical intervention to remove the hyperfunctioning parathyroid gland(s) or medical management to control calcium levels and mitigate associated symptoms and complications

In hyperparathyroidism, several laboratory tests may show abnormalities indicative of altered calcium and phosphorus metabolism. Additionally, the condition can lead to life-threatening complications. Here are the abnormal laboratory findings associated with hyperparathyroidism and the potential life-threatening complications:

1. Abnormal Laboratory Findings in Hyperparathyroidism:
   • Hypercalcemia: Serum calcium levels are typically elevated due to excessive release of parathyroid hormone (PTH), which promotes calcium mobilization from bones, increases renal calcium reabsorption, and enhances intestinal calcium absorption.
   • Hypophosphatemia: Blood phosphorus levels may be decreased as a result of increased renal excretion of phosphorus due to elevated PTH levels.
   • Elevated Serum Parathyroid Hormone (PTH): In primary hyperparathyroidism, serum PTH levels are typically elevated as a compensatory response to hypercalcemia. In secondary hyperparathyroidism, PTH levels may be elevated due to factors such as chronic kidney disease or vitamin D deficiency.
2. Life-Threatening Complications of Hyperparathyroidism:
   • Hypercalcemic Crisis: Severe hypercalcemia, particularly when acute or rapidly progressive, can lead to a hypercalcemic crisis, which is a life-threatening medical emergency. Hypercalcemic crisis is characterized by profound neurological, cardiovascular, and gastrointestinal manifestations, including confusion, lethargy, coma, cardiac arrhythmias, renal failure, pancreatitis, and gastrointestinal bleeding. Prompt recognition and aggressive treatment are essential to prevent complications and improve outcomes.
   • Renal Complications: Chronic hypercalcemia and hypercalciuria associated with hyperparathyroidism can increase the risk of kidney stones (nephrolithiasis) and nephrocalcinosis (calcium deposits in the kidneys). These renal complications can lead to obstructive uropathy, hydronephrosis, renal colic, urinary tract infections, and progressive kidney damage if left untreated. In severe cases, renal failure may occur.
   • Skeletal Complications: Prolonged hyperparathyroidism can result in skeletal manifestations such as osteoporosis, osteopenia, bone pain, pathologic fractures, and osteitis fibrosa cystica (a severe form of bone disease characterized by bone resorption, fibrosis, and cyst formation). These skeletal complications can significantly impair quality of life and mobility and increase the risk of fractures.
   • Cardiovascular Complications: Chronic hypercalcemia and dysregulated calcium metabolism associated with hyperparathyroidism can contribute to cardiovascular complications such as hypertension, left ventricular hypertrophy, vascular calcification, atherosclerosis, and increased risk of cardiovascular events including myocardial infarction and stroke.

Hyperparathyroidism can have profound effects on multiple organ systems and is associated with significant morbidity and mortality, particularly when complications such as hypercalcemic crisis occur. Early detection, appropriate management, and regular monitoring are crucial for optimizing outcomes in patients with hyperparathyroidism.

Verified by: Dr.Diab (March 29, 2024)

Citation: Dr.Diab. (March 29, 2024). What happens when parathyroid hormone is increased. Medcoi Journal of Medicine, 4(2). urn:medcoi:article32907.