What Is Hypercalcemia Caused by Milk?: Unraveling the Milk-Alkali Syndrome

November 8, 2025 •

4 min read

While hypercalcemia is the third most common cause of high calcium in hospitalized patients, after hyperparathyroidism and cancer, the risk associated with milk consumption itself is minimal. The condition known historically as the milk-alkali syndrome, or more accurately as calcium-alkali syndrome, explains what is hypercalcemia caused by milk and excessive alkali intake.

Quick Summary

Milk-alkali syndrome is a condition of high blood calcium (hypercalcemia) combined with metabolic alkalosis and kidney injury, resulting from excessive ingestion of calcium and absorbable alkali. While historically linked to diets containing milk and baking soda, today it is predominantly caused by overusing calcium carbonate supplements and antacids, particularly when combined with high vitamin D intake or kidney disease. Prompt diagnosis and treatment are essential for preventing severe complications.

Key Points

Modern Cause: The risk of hypercalcemia from milk-alkali syndrome (MAS) today stems primarily from overusing calcium carbonate supplements and antacids, not milk alone.
Metabolic Cycle: Excessive calcium and absorbable alkali intake suppress parathyroid hormone, leading to a harmful cycle of hypercalcemia, metabolic alkalosis, and impaired kidney function.
Recognize Symptoms: Symptoms range from mild (nausea, fatigue) to severe (confusion, renal failure) and require prompt medical attention.
Prevention is Key: Prevent CAS by monitoring total daily calcium intake from all sources, including supplements, fortified foods, and antacids.
Risk Factors: Those with chronic kidney disease, elderly individuals, and pregnant women are at higher risk of developing CAS.
Treatment: Management involves immediately stopping the intake of excess calcium and alkali, along with hydration, and monitoring by a healthcare professional.

Understanding the Resurgence of Milk-Alkali Syndrome

For most people, drinking a normal amount of milk poses no risk of causing hypercalcemia. However, the historic name 'milk-alkali syndrome' (MAS) and its modern resurgence are central to understanding how excessive calcium and absorbable alkali can lead to this metabolic disorder. The condition was first identified in the 1920s when a treatment for peptic ulcers, known as the 'Sippy diet,' involved frequent ingestion of large quantities of milk and sodium bicarbonate. This combination of calcium and absorbable alkali led to hypercalcemia, metabolic alkalosis, and impaired kidney function in some patients.

With the development of modern medications for ulcers, MAS became less common. However, it has seen a revival since the 1990s due to the widespread availability and use of over-the-counter calcium carbonate supplements and antacids. Today, it is more appropriately termed 'calcium-alkali syndrome' (CAS) to reflect that the primary culprits are supplements rather than dairy products alone. The syndrome is now frequently seen in older, postmenopausal women taking supplements to prevent osteoporosis, and in individuals self-medicating for dyspepsia with calcium carbonate tablets. The combination of high calcium carbonate intake with reduced kidney function and the use of certain medications can trigger the cycle of hypercalcemia, metabolic alkalosis, and potential renal failure.

The Pathophysiology of Calcium-Alkali Syndrome

At its core, calcium-alkali syndrome is a vicious cycle involving excess calcium, alkali, and kidney function. The process unfolds in several steps:

Excessive Calcium Intake: The syndrome begins with the ingestion of inappropriately high amounts of calcium, typically from supplements like calcium carbonate. While there is a Tolerable Upper Intake Level for calcium, MAS has been reported with varying levels of intake in susceptible individuals.
Increased Alkali Load: The intake of calcium carbonate, an absorbable alkali, contributes to metabolic alkalosis, an increase in the blood's pH.
Suppressed Parathyroid Hormone (PTH): As blood calcium levels rise, the parathyroid glands detect this excess and suppress the release of PTH.
Impaired Kidney Function: The hypercalcemia causes a concentration defect in the kidneys and can lead to volume depletion. Reduced kidney function impairs the body's ability to excrete excess calcium and, critically, bicarbonate.
Exacerbating Factors: The retained bicarbonate perpetuates the metabolic alkalosis, which in turn enhances calcium reabsorption in the kidneys' distal tubules, worsening the hypercalcemia. Dehydration resulting from the kidney concentrating defect further aggravates the condition.

Symptoms and Complications

Symptoms of hypercalcemia vary widely and can be subtle or severe, depending on the calcium level and the rate of its increase. It is crucial to recognize these warning signs, especially if you are taking supplements. Early symptoms often include:

Nausea and vomiting
Anorexia and weight loss
Headache, vertigo, and dizziness
Generalized weakness and fatigue

In more severe or chronic cases, the symptoms become more pronounced and can lead to serious complications:

Neurological: Confusion, lethargy, memory loss, and personality changes, potentially leading to stupor or coma in extreme cases.
Gastrointestinal: Constipation and abdominal pain.
Renal: Increased urination (polyuria), excessive thirst (polydipsia), formation of kidney stones (nephrolithiasis), and, most seriously, acute or chronic renal failure.
Cardiovascular: Shortened QT intervals on an electrocardiogram (ECG) and arrhythmias.

Comparing Historical and Modern Milk-Alkali Syndrome

The way Milk-Alkali Syndrome presents has evolved significantly from its original form. Understanding these differences can help clarify the risks associated with modern calcium supplementation.


Feature	Historical Milk-Alkali Syndrome (Sippy Diet)	Modern Calcium-Alkali Syndrome (CAS)
Primary Cause	Large quantities of milk and cream with absorbable alkali (sodium bicarbonate).	Over-the-counter calcium carbonate supplements and antacids.
Patient Population	Primarily men with peptic ulcer disease.	Postmenopausal women, pregnant women, and individuals using supplements for acid reflux.
Typical Duration	Prolonged use of the Sippy regimen.	Can be acute or chronic, depending on supplement intake.
Phosphate Levels	Often associated with hyperphosphatemia due to milk content.	Typically associated with normal to low phosphate levels.
Renal Outcome	Chronic, irreversible renal failure was common.	Renal function is often reversible, but permanent damage is possible in chronic cases.

Prevention and Treatment

Prevention is key, especially for individuals at higher risk, such as those with pre-existing kidney disease, the elderly, and pregnant women. The primary method of prevention is to be mindful of total daily calcium intake from all sources, including supplements, fortified foods, and antacids. It is recommended to discuss all supplementation with a healthcare provider, avoiding exceeding the Tolerable Upper Intake Level (UL). Lower amounts may be advisable for those with risk factors.

Treatment for CAS, once diagnosed, typically involves a few key steps:

Discontinuation: Immediately stop taking the calcium and alkali agents that caused the condition. This includes supplements like calcium carbonate and calcium-containing antacids.
Hydration: Aggressive intravenous or oral rehydration helps to lower calcium levels and correct volume depletion.
Medication: In severe cases, medications like loop diuretics or bisphosphonates may be used to enhance calcium excretion. In rare, refractory cases, dialysis might be necessary.
Dietary Adjustments: Temporary reduction of high-calcium foods and monitoring total calcium intake is necessary during treatment.

Conclusion

While the historic moniker links milk to this condition, it is a gross oversimplification of the true risk factors. The modern milk-alkali syndrome is predominantly driven by the overuse of calcium carbonate supplements, not moderate dairy intake. Individuals, particularly those with pre-existing health conditions or on multiple supplements, must be vigilant about their total calcium consumption to avoid this potentially serious condition. Always consult a healthcare professional before beginning any supplementation regimen to ensure it is appropriate and safe for your individual health needs. Early recognition and a careful medication history are vital for an accurate diagnosis and successful recovery. A useful resource for dietary calcium information can be found at the NIH Office of Dietary Supplements website.

Frequently Asked Questions

While milk contains calcium, drinking too much milk alone is not a common cause of hypercalcemia in modern times. Historically, it was a problem in the 'Sippy diet' when milk was consumed with large amounts of absorbable alkali. Today, the risk is more directly linked to overusing calcium carbonate supplements.

The primary cause of modern milk-alkali syndrome, now known as calcium-alkali syndrome, is the excessive and chronic intake of over-the-counter calcium carbonate supplements and antacids.

Early signs of MAS can be vague and include nausea, vomiting, loss of appetite, fatigue, weakness, headache, and confusion. It is important to see a healthcare provider if you experience these symptoms, especially while taking calcium supplements.

The Tolerable Upper Intake Level (UL) for calcium varies by age, and exceeding this amount increases risk. MAS has been reported with varying levels of intake in susceptible individuals, so it is essential to discuss appropriate intake with a healthcare provider, especially if you have pre-existing conditions.

High levels of vitamin D, often from over-supplementation, can worsen MAS by increasing the body's absorption of calcium. Vitamin D works with calcium, so excessive amounts of both can be problematic.

Treatment involves stopping the intake of the offending calcium and alkali agents, aggressive hydration to flush out excess calcium, and potentially medications in severe cases. Prompt treatment is key to reversing the condition and preventing permanent kidney damage.

Yes, older adults, particularly postmenopausal women taking calcium supplementation for osteoporosis, are at a higher risk. They may have reduced kidney function and less ability for their bones to buffer calcium loads, making them more susceptible.