Hypercalcemia is a condition characterized by higher-than-normal levels of calcium in the blood. This imbalance can impact various bodily functions, as calcium plays a crucial role in many physiological processes.
Understanding Hypercalcemia
Calcium is a mineral that supports numerous bodily functions, including bone formation, muscle contraction, nerve signal transmission, and heart rhythm regulation. The body tightly regulates blood calcium levels through hormones like parathyroid hormone (PTH) and calcitonin, along with vitamin D. Normal total blood calcium levels typically range from 8.5 to 10.2 milligrams per deciliter (mg/dL).
Hypercalcemia is categorized into different levels based on total serum calcium concentration. Mild hypercalcemia is defined as levels between 10.5 and 11.9 mg/dL. Moderate hypercalcemia falls within the range of 12.0 to 13.9 mg/dL. Severe hypercalcemia, often considered a medical emergency, occurs when calcium levels exceed 14.0 mg/dL.
Recognizing the Signs
The symptoms of hypercalcemia can vary significantly depending on the severity and how quickly calcium levels rise. In mild cases, individuals often experience no symptoms, and the condition may only be discovered during routine blood tests. However, some might notice subtle signs like increased thirst and more frequent urination.
As hypercalcemia progresses to moderate levels, symptoms become more noticeable and may include digestive issues such as constipation, nausea, and abdominal pain. Fatigue, muscle weakness, headaches, and general malaise can also develop. Neurological effects like confusion, forgetfulness, and depression may also begin to manifest.
In severe hypercalcemia, the symptoms can be debilitating and life-threatening. These include profound fatigue, lethargy, and significant mental status changes, potentially leading to stupor or coma. Cardiac abnormalities, such as abnormal heart rhythms, can also occur. Additionally, severe hypercalcemia can cause acute kidney injury.
Common Causes
The most frequent underlying cause of hypercalcemia is primary hyperparathyroidism, where one or more of the four small parathyroid glands in the neck produce too much parathyroid hormone (PTH). This excess PTH signals bones to release more calcium into the bloodstream and kidneys to reabsorb more calcium, leading to elevated levels. This condition is often due to a benign growth on a parathyroid gland.
Certain cancers are another major cause, contributing to a significant percentage of hypercalcemia cases. This is known as hypercalcemia of malignancy. Cancers can raise calcium levels through various mechanisms, such as producing a protein that mimics PTH (parathyroid hormone-related protein or PTHrP), directly breaking down bone through metastasis, or, less commonly, by producing excess active vitamin D. Cancers commonly associated with hypercalcemia include lung, breast, kidney, and multiple myeloma.
Other less common causes include excessive intake of vitamin D or calcium supplements, certain medications like thiazide diuretics or lithium, and prolonged immobility which can cause calcium to leach from bones. Dehydration can also temporarily elevate calcium concentrations due to reduced fluid volume in the blood. Some rare genetic conditions and diseases like sarcoidosis or tuberculosis can also contribute to high calcium levels.
The Path to Severe Complications
Prolonged or severely elevated calcium levels can lead to serious and potentially life-threatening complications by impairing the function of vital organs. The kidneys are particularly vulnerable, as excess calcium forces them to work harder to filter blood. This can result in increased urination and thirst, and over time, calcium deposits can form within the kidney tissue, leading to nephrocalcinosis and acute kidney injury or even chronic kidney failure.
The heart’s electrical system can also be disrupted by high calcium levels. Calcium plays a role in heart muscle contraction and electrical signaling, so an excess can lead to abnormal heart rhythms, such as bradycardia or other arrhythmias. These disturbances can be severe enough to cause cardiac arrest.
High calcium levels also affect the nervous system, leading to a range of neurological dysfunctions. Initially, this might manifest as confusion, lethargy, or fatigue, but in severe cases, it can progress to stupor and coma. The impact on the brain is due to calcium interfering with normal nerve conduction and cellular processes. The timeline for progression to these severe states is highly variable, depending on the underlying cause, the rate at which calcium levels increase, and the individual’s overall health status.
Diagnosis and Treatment
Diagnosing hypercalcemia typically begins with a blood test that measures total serum calcium levels. If this test shows an elevated calcium level, further blood tests are usually performed to confirm the diagnosis and determine the underlying cause. These additional tests may include measuring parathyroid hormone (PTH) levels, vitamin D levels, and parathyroid hormone-related protein (PTHrP), as well as assessing kidney function.
Initial treatment approaches for hypercalcemia focus on lowering calcium levels and managing symptoms. Intravenous fluids are often administered to rehydrate the patient and help the kidneys excrete excess calcium. Medications such as loop diuretics may also be used to promote calcium excretion, while bisphosphonates can help inhibit the breakdown of bone, thereby reducing calcium release into the blood. In cases of hypercalcemia of malignancy, denosumab, another bone-strengthening medication, may be used.
Addressing the underlying cause is a crucial part of long-term management. For primary hyperparathyroidism, surgical removal of the overactive parathyroid gland(s) can often cure the condition. If cancer is the cause, treating the malignancy itself through chemotherapy, radiation, or other targeted therapies is paramount. Prompt diagnosis and appropriate treatment are essential to prevent the severe complications associated with hypercalcemia.