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How CASR Gene Variants Affect Calcium Balance and Bone Health

Calcium is essential for strong bones and teeth, muscle function, nerve signaling, blood clotting, and hormone release. Most calcium is stored in bone, while blood calcium is tightly controlled by the body. The CASR gene makes the calcium sensing receptor, a protein that helps the parathyroid glands and kidneys monitor and fine tune blood calcium. Variations in CASR can nudge your set point for blood calcium, which may affect how your body responds to dietary calcium and other factors.

Why this matters for your health

  • Small differences in calcium regulation can influence bone strength, kidney stone risk, and a tendency for blood calcium to be near the high or low end of normal.
  • Most people do not need aggressive changes to diet or supplements. A food first approach, vitamin D sufficiency, adequate protein, weight bearing exercise, and reasonable hydration support healthy calcium balance.
  • If you have a personal or family history of kidney stones, parathyroid problems, or abnormal blood calcium tests, periodic monitoring and individualized guidance from your healthcare provider are important.

Practical daily guidance

  • Aim to meet but not exceed recommended calcium intake using food sources: dairy, fortified milks and juices, leafy greens, calcium set tofu, canned fish with bones, almonds and sesame products.
  • Space calcium containing meals across the day to improve absorption.
  • Ensure vitamin D sufficiency, as vitamin D helps the gut absorb calcium. Consider testing 25 hydroxy vitamin D if you or your clinician think levels may be low.
  • Include adequate protein and magnesium. Vitamin K supports bone metabolism and can be obtained from leafy greens.
  • Engage in regular weight bearing and resistance exercise to maintain bone strength.
  • Stay well hydrated and keep sodium intake moderate to lower kidney stone risk.
  • Avoid routine high dose calcium supplements unless a clinician recommends them for a specific medical reason.

When to check lab tests

  • If you have a family history of hypercalcemia or parathyroid disease, ask your clinician about periodic serum calcium and parathyroid hormone tests.
  • If you have recurrent kidney stones, discuss metabolic evaluation and 24 hour urine testing as appropriate.
  • Consider vitamin D testing if you have risk factors for deficiency or if your clinician wants to optimize bone health.

Genetic interpretation for rs17251221 (CASR)

The rs17251221 variant affects the CASR gene which encodes the calcium sensing receptor. Below are interpretations based on whether you carry two, one, or zero copies of the effect allele.

Two effect alleles (GG) — higher tendency toward higher blood calcium

If your genotype is GG, you carry two copies of the effect allele associated with a tendency toward higher blood calcium levels, usually within or close to the normal range. The calcium sensing receptor encoded by CASR may be slightly more sensitive, signaling your parathyroid glands and kidneys to maintain calcium at the higher end of normal.

What to do

  • Meet but do not exceed recommended daily calcium intake. Aim toward the lower end of target ranges if your clinician advises.
  • Prioritize food sources: dairy, fortified alternatives, leafy greens, canned fish with bones, calcium set tofu. Spread intake across meals.
  • Ensure vitamin D sufficiency through sun exposure, diet, or supplements if recommended by your clinician.
  • Get adequate protein, magnesium, and vitamin K to support bone health.
  • Do regular weight bearing and resistance exercise.
  • Avoid unnecessary high dose calcium supplements unless medically indicated.
  • Stay hydrated and moderate sodium to reduce kidney stone risk.
  • If you have a personal or family history of high calcium, kidney stones, or parathyroid disease, discuss periodic serum calcium and tailored intake targets with your healthcare provider.
One effect allele (GA) — moderately higher tendency for blood calcium

If your genotype is GA, you carry one copy of the effect allele. This is associated with a modest tendency for blood calcium to be toward the higher end of the normal range. Your calcium sensing receptor may signal to keep calcium slightly higher than average.

Practical actions

  • Maintain a food first approach to calcium. Meet but do not exceed recommended daily intake.
  • Choose calcium rich foods such as dairy, fortified foods, leafy greens, and calcium set tofu and distribute them across the day.
  • Confirm vitamin D sufficiency and get adequate protein, magnesium, and vitamin K for bone support.
  • Engage in regular weight bearing and resistance exercise.
  • Stay hydrated, limit excess sodium, and avoid routine high dose calcium supplements unless advised by a clinician.
  • If you have a history of kidney stones or prior elevated calcium tests, discuss periodic monitoring with your clinician to personalize recommendations.
No effect alleles (AA) — typical calcium regulation

If your genotype is AA, you carry two copies of the non effect allele and have the typical CASR profile associated with normal calcium regulation. Your calcium sensing receptor functions in the standard way to keep blood calcium within the usual range.

Recommended approach

  • Follow general population guidelines for calcium. Aim to meet daily targets through food.
  • Include dairy, fortified alternatives, leafy greens, and canned fish with bones in your diet and spread them through the day.
  • Ensure vitamin D sufficiency, adequate protein, magnesium, and vitamin K.
  • Do weight bearing and resistance exercise regularly.
  • Reserve high dose calcium supplements for situations where a clinician prescribes them. Maintain hydration and moderate sodium.

Supplement considerations

  • Vitamin D: Often the first supplement to consider for bone support. Have levels checked when appropriate and follow your clinician's dosing guidance.
  • Calcium supplements: Use only if dietary intake falls short and a clinician recommends supplementation. High dose calcium without medical indication can raise risk of kidney stones for some people.
  • Magnesium and vitamin K: Support bone and mineral metabolism and can be included as part of a balanced approach when diet is insufficient.

Lifestyle habits that help

  • Weight bearing activities such as walking, jogging, dancing, and strength training build and maintain bone mass.
  • A balanced diet with a variety of calcium containing foods is preferred over supplements whenever possible.
  • Avoid smoking and limit heavy alcohol use, both of which negatively affect bone health.
  • Stay hydrated and keep salt intake moderate to reduce urinary calcium loss and kidney stone risk.

Important notes and next steps

PlexusDx provides educational information about genetic predispositions. This content is not medical advice. Always consult your healthcare provider before making changes to diet, supplements, or medical care. If you have a history of kidney stones, abnormal calcium tests, or parathyroid disease, work with your clinician for personalized testing and management. If you want to optimize vitamin D or calcium status, ask your clinician about testing 25 hydroxy vitamin D and serum calcium and whether 24 hour urine testing is appropriate for you.