Your Bone Bank Balance
Your body obsessively maintains blood calcium within a tight range because calcium controls muscle contraction (including your heart), nerve signaling, and blood clotting. Your bones are the savings account—99% of your calcium lives there. When blood calcium dips, your body withdraws from bones. When it's high, something is forcing calcium out of storage.
What is Calcium (Serum)?
Serum calcium measures total calcium (bound to albumin + free ionized). About 40% is bound to albumin, so low albumin falsely lowers total calcium. Corrected calcium or ionized calcium gives a more accurate picture. Normal range is tightly maintained at 8.5-10.5 mg/dL.
↑ What High Calcium (Serum) Means
Calcium is being pulled out of bones or absorbed excessively. The #1 cause is hyperparathyroidism (overactive parathyroid glands). #2 is cancer. High calcium causes fatigue, confusion, kidney stones, constipation—"bones, stones, groans, and moans."
Common symptoms:
Fatigue and weakness · Confusion and brain fog · Kidney stones · Constipation · Bone pain · Excessive thirst and urination · Nausea · Cardiac arrhythmias
↓ What Low Calcium (Serum) Means
Either calcium intake is genuinely low, or your body can't maintain levels (low vitamin D, low parathyroid hormone, or low albumin making the test look falsely low). True low calcium causes muscle cramps, tingling, and in severe cases, seizures.
Common symptoms:
Muscle cramps and spasms · Numbness and tingling (perioral, fingertips) · Tetany (severe muscle contractions) · Seizures (severe) · Brittle nails · Osteoporosis long-term
Why It Matters
When normal:
Essential for bone strength
Muscle contraction (including heart)
Nerve impulse transmission
Blood clotting
Risks if abnormal:
High: kidney stones, bone loss, cardiac arrhythmias, confusion, constipation
Low: muscle cramps, tetany, seizures, osteoporosis long-term
Always correct for albumin level
What Can Cause Abnormal Levels?
Primary Hyperparathyroidism (high)
55% likelyA benign parathyroid tumor overproduces PTH, pulling calcium from bones into blood. Most common cause of high calcium.
Vitamin D Deficiency (low)
50% likelyWithout vitamin D, you can't absorb calcium from food. Body raids bones to maintain blood levels.
Cancer (high)
Some cancers produce PTH-related peptide or directly destroy bone, releasing calcium.
Low Albumin (falsely low)
Since 40% of calcium is bound to albumin, low albumin makes total calcium look low while ionized (actual) calcium is normal.
Kidney Disease
Kidneys activate vitamin D and excrete calcium. Kidney failure disrupts both.
What You Can Do
Calcium-rich foods: dairy, sardines with bones, fortified plant milk, broccoli, kale
Impact: Food calcium is better absorbed and safer than supplements \u00B7 Timeline: 4-8 weeks
Optimize vitamin D (needed to absorb calcium)
Impact: Without vitamin D, dietary calcium is poorly absorbed \u00B7 Timeline: 8-12 weeks
Vitamin K2: 100-200mcg daily (directs calcium to bones, not arteries)
Impact: Ensures calcium goes where it should \u00B7 Timeline: 3-6 months
If lifestyle changes aren't enough:
Calcium supplement if dietary intake insufficient: 500mg calcium citrate with meals
Impact: Citrate form absorbs better than carbonate, especially with low stomach acid \u00B7 Timeline: 4-8 weeks
Weight-bearing exercise
Impact: Stimulates bones to retain calcium \u00B7 Timeline: 4-8 weeks
Limit excess sodium (high sodium increases calcium excretion in urine)
Impact: Preserves calcium stores \u00B7 Timeline: 2-4 weeks
Recommended retest: 3-6 months; sooner if abnormal
Related Markers
Got your blood test report?
Upload your PDF and understand ALL your markers in 2 minutes. Plain language. Traffic light status. No medical jargon.
Analyze My Report — FreeFirst report is free. No credit card needed.