Calcium and Parathyroid Hormone (PTH) Profile with Genetic Analysis (if applicable)
This test measures your blood levels of calcium and parathyroid hormone (PTH), along with optional genetic screening for variations that may affect calcium metabolism.
["Understanding your calcium and hormone balance helps manage bone health and prevent complications like osteoporosis or abnormal heart rhythms."]
Key facts at a glance
- LOINC
- 21755-4
- Short code
- CACNA1A-CAG
- Synonyms
- CACNA1A gene CAG Rpt Bld/T Ql
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA tube (lavender-top) for whole blood; sterile container for tissue specimen
- Units
- N/A
- Ref low
- 4
- Ref high
- 13
- Critical range
- — – 17 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- molgen
- CPT
- 81228
- SNOMED
- 410950007
- Specimen volume
- 3-5 mL whole blood; 5-10 mg tissue
- Stability
- Whole blood: 7 days at 2-8°C; 1 month at -20°C; indefinitely at -80°C. Tissue: 24 hours at room temperature in sterile saline, longer storage at -80°C.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 168–720 hours
- Order
- routine
What This Test Measures
Calcium (Ca²⁺) is a mineral essential for nerve function, muscle contractions, and bone strength. PTH is a hormone produced by your parathyroid glands that regulates calcium levels in your blood. Together, these help maintain healthy mineral balance.
Why It Matters in Your Health
Abnormal calcium levels can lead to conditions such as kidney stones, muscle weakness, or irregular heart rhythms. PTH helps regulate these levels, so monitoring both can help prevent long-term health issues.
Common Reasons for Testing
Your doctor may order this test if you have symptoms like frequent bone pain, frequent urination, muscle spasms, or if you have a history of conditions like osteoporosis, kidney disease, or hyperthyroidism.
Sample Collection and Preparation
A blood sample is drawn from a vein in your arm. This test may also include optional genetic testing, which requires a separate blood sample or saliva sample for analysis.
Reference range
Normal: <13 CAG repeats (typical normal range 4-13). Intermediate (mutable normal): 13-17 repeats. Pathogenic expansion: ≥18 CAG repeats. Note: Allele sizes may vary slightly between laboratories; clinical correlation required.N/A
No fasting required. Genetic counseling is recommended prior to testing. Informed consent should be obtained. Patient should be informed that results may have implications for family members.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
What does a normal result mean?
How often should I get this test?
Can diet or supplements affect this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy