What happens when the blood calcium level is too low

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Effects of Low Blood Calcium Levels

Hypocalcemia and Parathyroid Hormone Activation

When blood calcium levels drop too low, a condition known as hypocalcemia, the body initiates several compensatory mechanisms to restore calcium balance. The parathyroid glands play a crucial role in this process. They release parathyroid hormone (PTH) in response to low calcium levels, which mobilizes calcium from the bones into the bloodstream to normalize calcium levels 35. This feedback mechanism ensures that calcium levels are maintained within a narrow range to support vital physiological functions.

Impact on Blood Pressure

Low calcium levels can significantly affect blood pressure. Research indicates that a low calcium diet can lead to increased blood pressure through several mechanisms. PTH increases intracellular calcium in vascular smooth muscle cells, causing vasoconstriction, which raises blood pressure 12. Additionally, low calcium intake can stimulate the renin-angiotensin-aldosterone system, further contributing to hypertension 12. Studies on animals, such as pregnant rats on a calcium-free diet, have shown a significant rise in blood pressure, supporting the link between low calcium intake and hypertension .

Hypocalcemia in Trauma and Critical Illness

In trauma patients, hypocalcemia is a common issue, especially after significant blood loss and transfusion. Blood products contain citrate, which chelates calcium, leading to a drop in ionized calcium levels. This can result in hypotension and increased mortality if not promptly addressed . Critically ill patients often experience severe hypocalcemia, which is challenging to correct with standard calcium therapy. This condition can exacerbate hemodynamic instability, making it crucial to monitor and manage calcium levels closely in these patients .

Conclusion

Low blood calcium levels trigger a series of physiological responses aimed at restoring calcium balance, primarily through the action of the parathyroid hormone. However, hypocalcemia can have significant adverse effects, including increased blood pressure and complications in trauma and critically ill patients. Understanding these mechanisms is essential for effective management and treatment of hypocalcemia to prevent associated health risks.

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Most relevant research papers on this topic

Mechanisms Involved in the Relationship between Low Calcium Intake and High Blood Pressure

Low calcium intake increases blood pressure through increased parathyroid hormone activity and calcitriol synthesis, potentially affecting renin release and angiotensin II and aldosterone synthesis.

Literature ReviewVery Rigorous JournalHighly Cited

2019·

95citations

·Cecilia Villa-Etchegoyen et al.

Calcium Intake and Health

Increasing calcium intake to 400-500 mg/day can reduce blood pressure, reduce osteoporosis risk, and lower cholesterol levels, with potential benefits for both rich and poor populations.

Very Rigorous JournalHighly Cited

2019·

267citations

·G. Cormick et al.

Calcitonin—a Hormone from the Parathyroid which Lowers the Calcium-level of the Blood

Calcitonin, a hormone from the parathyroid gland, lowers blood calcium levels by stimulating the gland to produce parathyroid hormone, which mobilizes calcium from bone and restores normal levels.

Highly Cited

1962·

133citations

·D. Copp et al.

Rise of blood pressure in calcium-deprived pregnant rats.

A low-calcium diet is associated with high blood pressure in both pregnant and nonpregnant female rats.

RCTAnimal StudyHighly Cited

1981·

80citations

·J. Belizán et al.

Evidence for calcitonin--a new hormone from the parathyroid that lowers blood calcium.

Calcitonin, a new hormone from the parathyroid gland, lowers blood calcium levels by inhibiting parathormone production in hypercalcemia.

Highly Cited

1962·

637citations

·D. Copp et al.

Ionised calcium levels in major trauma patients who received blood in the Emergency Department

Trauma patients with blood loss are at risk of hypocalcaemia, and receiving even a small amount of blood product can significantly worsen this state.

Observational Study

2016·

52citations

·S. Webster et al.

Low Plasma Ionized Calcium and Response to Calcium Therapy in Critically Ill Man

Low plasma ionized calcium levels in critically ill patients often cannot be corrected by calcium therapy alone, and calcium replacement therapy should be closely monitored.

Case ReportHighly Cited

1975·

105citations

·L. Drop et al.

Relation between low calcium intake, parathyroid hormone, and blood pressure.

Reduced calcium intake is frequently associated with high levels of serum parathyroid hormone, which can lead to reduced bone mineral content and density in the lumbar spine, and increased blood pressure in women.

Observational StudyHighly Cited

2000·

113citations

·R. Jorde et al.

The effects of calcium supplementation to patients with primary hyperparathyroidism and a low calcium intake

Most patients with mild primary hyperparathyroidism and low calcium intake tolerate a moderate calcium supplement, potentially improving bone mineral density, but careful monitoring is needed.

Non-RCT

2002·

43citations

·R. Jorde et al.

Modification of platelet and lymphocyte calcium handling and blood pressure by dietary sodium and calcium in genetically hypertensive rats.

Dietary sodium and calcium levels influence blood pressure and cellular calcium handling, with high sodium-low calcium diets increasing blood pressure and affecting platelet and lymphocyte calcium handling.

Non-RCTAnimal Study

1992·

17citations

·T. Oshima et al.

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