Hyperparathyroidism (Abnormally High Parathyroid Hormone Levels, Overactive Parathyroid Glands) in cats

  • Occurrence: rarer
  • Location of illness: General/Whole body, Head/Neck
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Hyperparathyroidism in cats is a condition in which the parathyroid glands produce excessive parathyroid hormone (PTH), leading to abnormally high calcium levels in the blood.

The most important facts at a glance

Hyperparathyroidism in cats is a condition in which the parathyroid glands produce too much parathyroid hormone (PTH), leading to an increased calcium level in the blood. These glands are crucial for calcium metabolism. Primary hyperparathyroidism often results from benign tumors that stimulate the glands to overproduce PTH. Secondary hyperparathyroidism often occurs with chronic calcium deficiency or kidney disease, while the tertiary form can result from a long-standing secondary condition. Symptoms include increased thirst, loss of appetite, and lethargy. Diagnosis is made by blood tests and imaging procedures such as ultrasound. Treatment depends on the cause: surgical removal of the affected glands in primary hyperparathyroidism and therapy of the underlying disease in the secondary form. The prognosis is often good with timely treatment, especially if there is no kidney damage. Preventive measures include a balanced diet and regular veterinary check-ups. Research focuses on genetic factors, improved diagnostics, and new treatment methods, including drug therapies and nutrition. These efforts aim to improve the quality of life of affected cats and optimize the management of the disease.

Causes

The parathyroid glands are small glands located near, or sometimes within, the thyroid gland. They play a crucial role in calcium metabolism by producing parathyroid hormone (PTH), which regulates the concentration of calcium in the blood. When calcium in the blood is low, more PTH is released to increase calcium absorption in the intestine, promote calcium release from the bones, and increase calcium reabsorption in the kidneys.

Primary hyperparathyroidism occurs when one or more of the parathyroid glands function autonomously and produce excessive PTH, regardless of the body’s actual calcium needs. This leads to hypercalcemia, i.e., an elevated calcium level in the blood. The most common cause of primary hyperparathyroidism are benign tumors, called adenomas, that affect the parathyroid glands.

Secondary hyperparathyroidism often develops as a response to chronic calcium deficiency or chronic kidney disease. In chronic kidney failure, the kidneys cannot efficiently excrete phosphate, leading to an increase in phosphate concentration and a relative calcium deficiency, which in turn stimulates the parathyroid glands to produce PTH.

Another form, tertiary hyperparathyroidism, can develop from long-standing secondary hyperparathyroidism, in which the parathyroid glands become autonomous and produce PTH uncontrollably.

Symptoms

Rare symptoms:

The symptoms of hyperparathyroidism in cats can be subtle and non-specific, making diagnosis difficult. However, the most common signs include increased thirst (polydipsia) and increased urination (polyuria). These symptoms occur because hypercalcemia can impair the kidneys’ ability to concentrate urine.

Other possible symptoms include loss of appetite, weight loss, vomiting, and lethargy. Due to the increased calcium concentration in the blood, muscle weakness and bone pain may also occur. In severe cases, neurological symptoms such as disorientation or even convulsions may occur.

Chronic hypercalcemia can also lead to kidney damage, as the kidneys are stressed by excessive calcium excretion. This can manifest as a deterioration of kidney function, which can further exacerbate the symptoms.

Diagnosis

The diagnosis of hyperparathyroidism in cats is made through a combination of clinical signs, blood tests, and imaging procedures. The first step is usually a blood test to determine the calcium and phosphate levels in the blood. An elevated calcium level in conjunction with an elevated or inappropriately normal PTH level indicates hyperparathyroidism.

In addition, an ultrasound examination of the neck region can be performed to visualize the parathyroid glands. Enlarged or abnormal parathyroid glands may indicate an adenoma or hyperplasia. In some cases, scintigraphy may be helpful in assessing the function of the parathyroid glands.

A careful history and physical examination are also important to rule out other causes of hypercalcemia, such as certain cancers or vitamin D intoxication.

Therapy

The treatment of hyperparathyroidism in cats depends on the underlying cause. In primary hyperparathyroidism caused by an adenoma, surgical removal of the affected parathyroid gland is the preferred therapy. This surgery can be performed relatively safely by an experienced veterinary professional.

For cats with secondary hyperparathyroidism, treating the underlying disease is crucial. In chronic kidney disease, this may include dietary adjustments, phosphate binders, and other supportive therapies to regulate calcium and phosphate balance.

In some cases, drug therapy with calcimimetics, which simulate the effect of calcium on the parathyroid glands and reduce PTH production, may be necessary. These drugs can help stabilize calcium levels, especially when surgery is not possible.

Prognosis and follow-up care

The prognosis for cats with hyperparathyroidism varies depending on the cause and treatment. In cats that have been successfully operated on to remove a parathyroid adenoma, the prognosis is generally good, especially if there is no permanent kidney damage.

For cats with secondary hyperparathyroidism, the prognosis depends on the underlying disease. Early and appropriate treatment can slow the progression of the disease and improve the quality of life, but the long-term prognosis is often guarded, especially in advanced kidney disease.

Continuous monitoring and regular veterinary check-ups are crucial to monitor the course of treatment and make adjustments if necessary.

Prevention

To prevent hyperparathyroidism in cats, it is important to pay attention to a balanced diet that meets the specific nutritional needs of the cat. A balanced diet helps to ensure the right amount of calcium and phosphorus, which is crucial for the health of the parathyroid glands. Veterinarians can recommend special diets tailored to the needs of cats to reduce the risk of overactive parathyroid glands.

Regular veterinary check-ups are also important to monitor the cat’s health. Blood tests can detect abnormalities in calcium and phosphorus levels early, allowing for early intervention. Pet owners should also ensure that their cats drink enough water to support kidney function, as kidney problems can be associated with an imbalance of minerals in the body.

A stress-free environment and sufficient exercise also contribute to the cat’s general health. Stress can weaken the immune system and increase the likelihood of hormone imbalances. By paying attention to these factors, the risk of hyperparathyroidism in cats can be reduced.

Outlook on current research

Current research on hyperparathyroidism in cats has gained importance in recent years, as understanding this condition is crucial for the effective treatment and management of affected animals. A key direction of research focuses on the genetic factors that may contribute to the development of this condition. Researchers are investigating whether there are specific genetic markers that predispose cats to develop overactive parathyroid glands. These studies are important to identify potential risks early and develop preventive measures.

Another significant area of research is concerned with improving diagnostic methods. Currently, many diagnoses are based on blood tests to measure parathyroid hormone levels, but these tests can be influenced by other factors. New techniques, such as imaging diagnostics using ultrasound or CT scans, are being investigated for their effectiveness in visualizing structural changes in the parathyroid glands. These technologies could help to make more accurate diagnoses and reduce the need for invasive procedures.

Research into the treatment of hyperparathyroidism in cats has also made significant progress. While surgical procedures to remove the affected glands are a traditional treatment method, less invasive alternatives are being intensively researched. These include drug therapies that aim to regulate parathyroid hormone production or block the hormone’s effect on the body. Studies on new drugs that specifically target the molecular mechanisms of the disease show promising results. These drugs could not only alleviate the symptoms, but possibly also slow the progression of the disease.

Another area of research is investigating the role of nutrition and lifestyle in the development and treatment of hyperparathyroidism. There is evidence that certain diets, especially those with a high calcium or vitamin D content, can influence the disease. Scientists are exploring how dietary adjustments can be used for prevention or as a supportive therapy. The role of environmental factors and stress in the development of the disease is also being investigated.

In summary, research on hyperparathyroidism in cats is moving in several directions. From genetic predisposition to improving diagnostic procedures to new treatment approaches and prevention strategies – all these efforts aim to improve the lives of cats with this condition and increase their quality of life. Advances in scientific research promise to fundamentally change management strategies for this complex disease.

Frequently asked questions (FAQs)

  1. What is Hyperparathyroidism in Cats? Hyperparathyroidism in cats is a condition in which the parathyroid glands produce too much parathyroid hormone (PTH). This hormone regulates calcium and phosphate metabolism in the body, and an excess can lead to health problems.

  2. What symptoms does a cat with hyperparathyroidism show? The most common symptoms include increased thirst and increased urination, loss of appetite, weight loss, vomiting, and weakness. In some cases, bone pain or fractures may also occur.

  3. How is hyperparathyroidism diagnosed in cats? The diagnosis is usually based on blood tests that show elevated calcium and parathyroid hormone levels. Further tests such as X-rays or ultrasound may be necessary to identify changes in the parathyroid glands.

  4. What causes hyperparathyroidism in cats? The condition can be primary or secondary. Primary hyperparathyroidism is often caused by benign tumors of the parathyroid glands. Secondary hyperparathyroidism can be triggered by kidney failure or a vitamin D deficiency.

  5. How is hyperparathyroidism treated in cats? Treatment may include surgical removal of the affected glands or the use of medications to regulate hormone production. A special diet can also help to keep calcium levels in balance.

  6. Is hyperparathyroidism curable in cats? In many cases, a complete cure can be achieved through successful surgery. In secondary hyperparathyroidism, the prognosis depends on the treatment of the underlying cause, such as kidney disease.

  7. Can all cats get hyperparathyroidism? Yes, theoretically all cats can get hyperparathyroidism, but it is more common in older cats. Certain breeds may be at higher risk due to genetic factors.

  8. What role does nutrition play in hyperparathyroidism? A balanced diet is important to support the calcium and phosphate balance in the body. Special diets can help control symptoms and avoid complications.

  9. Can hyperparathyroidism be prevented in cats? Complete prevention is difficult, but regular veterinary check-ups and a balanced diet can help reduce the risk. Early detection of symptoms is crucial for successful treatment.

  10. How does hyperparathyroidism affect a cat’s quality of life? Without treatment, hyperparathyroidism can significantly impair the quality of life, as symptoms such as weakness and loss of appetite severely limit the cat’s well-being. With appropriate treatment, however, many cats can lead a normal life.

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