Demystifying Hyperparathyroidism and Hypoparathyroidism: A Guide

Miss medicine
Oct 12, 2023
4 min read

Updated: Oct 23, 2023

The Parathyroid Glands: Guardians of Calcium Balance

The four parathyroid glands, despite their small size and discreet location near the thyroid, play a significant role in regulating calcium levels in the body.

Their primary function is to secrete parathyroid hormone (PTH), which is stimulated by low serum calcium and/or low levels of vitamin D. The parathyroid hormone (PTH) plays a vital role in maintaining the delicate balance of calcium in the body.
PTH exerts its effects primarily on the bones, kidneys, and intestines, helping to regulate calcium levels in the bloodstream.

When these glands malfunction, it can lead to two distinct conditions: hyperparathyroidism and hypoparathyroidism. In this blog post, we will explore these conditions, their causes, symptoms, diagnosis, and available treatment options.

Before we delve into the conditions themselves, let's understand the parathyroid glands' crucial role. There are typically four of these tiny glands, each no larger than a grain of rice.

THE PARATHYROID GLANDS’ ROLE IN THE BODY:

Bone Regulation:

One of PTH's primary functions is to regulate the release of calcium from bones. When blood calcium levels drop, the parathyroid glands release PTH. PTH stimulates osteoclasts, cells responsible for breaking down bone tissue. This process releases calcium from the bones into the bloodstream, increasing blood calcium levels.

Kidney Regulation:

PTH also plays a significant role in the kidneys. It encourages the reabsorption of calcium in the renal tubules while simultaneously increasing the excretion of phosphate. This action helps to conserve calcium and excrete excess phosphate, further increasing blood calcium levels.

Intestinal Regulation:

PTH indirectly influences the absorption of dietary calcium in the intestines by promoting the activation of vitamin D. Vitamin D is essential for the efficient absorption of calcium from the gut, and PTH stimulates the conversion of inactive vitamin D into its active form, which, in turn, enhances calcium uptake from the intestines.

REGULATION OF PTH:

The tight regulation of PTH ensures that blood calcium levels remain within a narrow range, vital for various physiological processes, including muscle contraction, nerve signaling, and bone health. PTH secretion is tightly regulated by a feedback mechanism that responds to changes in blood calcium levels:

When blood calcium levels are low, specialized cells in the parathyroid glands, known as chief cells, sense this drop and increase their secretion of PTH.
In contrast, when blood calcium levels are high, the secretion of PTH is suppressed to prevent hypercalcemia, a condition characterized by excessive calcium in the blood.

Factors influencing PTH regulation include:

Blood Calcium Levels:

Low blood calcium levels stimulate PTH release, while high levels inhibit its secretion.

Vitamin D:

Adequate levels of vitamin D are necessary for PTH to function effectively in promoting calcium absorption in the intestines.

Phosphate Levels:

High blood phosphate levels can suppress PTH secretion. The inverse relationship between PTH and phosphate levels is essential to prevent an excessive release of calcium from the bones.

DISEASES OF THE PARATHYROID GLANDS:

Diseases of the parathyroid glands are classified into hyperparathyroidism, characterized by excessive production of PTH, and hypoparathyroidism, characterized by insufficient hormone production.

HYPERPARATHYROIDISM: THE OVERACTIVE PARATHYROID

Hyperparathyroidism is a condition characterized by the excessive production of parathyroid hormone (PTH) by the parathyroid glands.

There are three types of hyperparathyroidism, based on its cause: primary, secondary, and tertiary.

Regardless of the type, all forms of hyperparathyroidism involve increased production of parathyroid hormone (PTH), which stimulates the breakdown and loss of minerals from the skeleton, resulting in high levels of calcium in the blood (hypercalcemia).
The most severe manifestation of this bone loss is called osteitis fibrosa cystica. When there is insufficient vitamin D supply or the vitamin is less effective, the demineralization of the skeleton occurs more rapidly because vitamin D plays a crucial role in the absorption of calcium in the small intestine.

Causes:

Hyperparathyroidism occurs when one or more of the parathyroid glands produce too much PTH. The common culprits are benign tumors on the glands, known as adenomas, or gland enlargement. This excess PTH leads to elevated calcium levels in the bloodstream.

Symptoms:

Fatigue Muscle weakness Kidney stones Bone pain and osteoporosis Digestive issues Frequent urination Depression and cognitive impairment

Diagnosis:

Blood tests to check calcium and PTH levels, as well as imaging scans to locate enlarged glands or tumors, are often used to diagnose hyperparathyroidism.

Treatment:

Surgery to remove the affected gland(s) is the primary treatment. Lifestyle changes, such as dietary adjustments and increased hydration, can help manage symptoms.

PRIMARY HYPERPARATHYROIDISM:

This is the most common type and is usually caused by a parathyroid adenoma (while hyperplasia or cancer are uncommon causes).
It is more prevalent in older women.
Primary hyperparathyroidism reulsts in too much production of PTH (parathyroid hormone), leading to hypercalcemia (too much calcium in the blood).
Other conditions that can lead to high levels of calcium include malignant diseases (caused by the spread of cancer to the bones or production of parathyroid hormone-like peptides (PTHrP)), sarcoidosis, and chronic vitamin D poisoning. The diagnosis of primary hyperparathyroidism is based on identifying high levels of calcium and elevated parathyroid hormone levels. Parathyroid adenoma is typically treated with surgery.

SECONDARY HYPERPARATHYROIDISM:

Secondary hyperparathyroidism occurs as a response to long-term hypocalcemia, usually caused by conditions such as: vitamin D deficiency, chronic kidney failure, or malabsorption disorders (e.g. intestinal disorders such as celiac disease).
This leads to constant stimulation of the parathyroid glands, causing them to enlarge and produce excessive PTH (parathyroid hormone).
The specific symptoms of secondary hyperparathyroidism vary depending on the underlying disease.
Treatment involves addressing the underlying cause and providing calcium and vitamin D supplementation, with vitamin D supplements alone being sufficient if the cause is a deficiency of this vitamin.

TERTIARY HYPERPARATHYROIDISM:

Tertiary hyperparathyroidism develops when secondary hyperparathyroidism persists despite treatment of the underlying cause. Prolonged stimulation of the parathyroid glands leads to the enlargement and independent function of these glands (autonomously functioning), which causes the continuous production of high levels of parathyroid hormone and hypercalcemia.
Tertiary hyperparathyroidism is commonly observed in patients with chronic kidney disease or those who have undergone kidney transplantation.
Treatment usually involves surgical removal of the enlarged parathyroid tissue.

HYPOPARATHYROIDISM: THE UNDERACTIVE PARATHYROID

Hypoparathyroidism is a condition characterized by not enough production of parathyroid hormone (PTH) by the parathyroid glands.

The leading cause of hypoparathyroidism is typically the result of damage or removal of the parathyroid glands during thyroid surgery. Alternatively, the condition can be autoimmune in nature, where the production of antibodies against the parathyroid tissue leads to gland damage. It can also be caused by congenital hypoplasia of the glands, as seen in cases of DiGeorge syndrome (genetic condition).
Hypoparathyroidism causes low levels of calcium in the blood, a condition known as hypocalcemia. The most common symptoms include tingling or numbness in the mouth, fingers, and toes, as well as muscle spasms. A rapid decrease in blood calcium levels can often result in cramps or tetany. The diagnosis is made by identifying low levels of blood calcium and parathyroid hormone.
Prompt treatment is necessary to prevent complications like seizures. In the event of seizures, intravenous calcium is administered. The treatment typically involves taking oral calcium supplements and vitamin D, which enhances calcium absorption in the intestines. It is important to regularly monitor serum calcium levels to avoid an overdose of vitamin D and subsequent high levels of calcium in the blood (hypercalcemia).

Causes:

Hypoparathyroidism results from damaged or improperly functioning parathyroid glands, often due to surgery or autoimmune diseases. In this condition, insufficient PTH leads to low blood calcium levels.

Symptoms:

Muscle cramps and spasms Numbness and tingling Fatigue Weak bones and fractures Anxiety and depression Dental problems Cognitive issues

Diagnosis:

Blood tests to measure calcium and PTH levels, as well as electrocardiograms to detect heart irregularities caused by low calcium, are key to diagnosing hypoparathyroidism.

Treatment:

The primary treatment involves calcium and vitamin D supplementation to raise and maintain calcium levels within the normal range. Close monitoring by healthcare professionals is essential.

LIVING WITH PARATHYROID IMBALANCES:

COPING STRATEGIES

Both hyperparathyroidism and hypoparathyroidism can significantly impact your quality of life.

To cope effectively, consider the following strategies:

Medical Management:

Regular check-ups with an endocrinologist are crucial for monitoring your condition and adjusting treatment as needed.

Dietary Changes:

In both conditions, dietary choices can play a significant role. Consult with a nutritionist to create a balanced diet that supports your health.

Lifestyle Modifications:

Physical activity, stress management, and adequate hydration are vital for overall well-being.

Mental Health Support:

Seek support from mental health professionals or support groups to manage any emotional or psychological challenges that may arise.

Parathyroid gland disorders are manageable, and early diagnosis and treatment can help prevent complications. If you suspect you might have a parathyroid-related issue, don't hesitate to consult a healthcare professional for a thorough evaluation.
Understanding these conditions and their treatment options is a crucial step in taking control of your health and ensuring a balanced and happy life despite parathyroid imbalances.
In summary, hyperparathyroidism involves excessive production of PTH, leading to high levels of calcium in the blood (hypercalcemia), while hypoparathyroidism involves not enough production of PTH, resulting in low levels of calcium in the blood (hypocalcemia). Both conditions require appropriate management to restore calcium balance and prevent complications.

SOURCES:

Jacobsen, D., Kjeldsen, S., Ingvaldsen, B., Buanes, T., & Roise, O. (2021). Sykdomslære: Indremedisin, Kirurgi og Anestesi (4th edition). Gyldendal.

Walker MD, Silverberg SJ. Primary hyperparathyroidism. Nat Rev Endocrinol. 2018 Feb;14(2):115-125. doi: 10.1038/nrendo.2017.104. Epub 2017 Sep 8. PMID: 28885621; PMCID: PMC6037987.

Muppidi V, Meegada SR, Rehman A. Secondary Hyperparathyroidism. [Updated 2023 Feb 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557822/

Bilezikian JP. Hypoparathyroidism. J Clin Endocrinol Metab. 2020 Jun 1;105(6):1722–36. doi: 10.1210/clinem/dgaa113. PMID: 32322899; PMCID: PMC7176479.