Meta Information
ID:strontium
Name:
Schema Version:2.4_uniform_evidence_2026_06_18
Created
2026-05-21T22:30:00Z
Model
phase-a-upgrade-claude-sonnet-4.6
Interactions
Target id:
/dietary/calcium-rich-foods
Target name:
Calcium-Rich Foods (e.g., Dairy)
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
Strontium and calcium are chemically similar and compete for the same absorption pathways in the intestine, which drastically reduces the absorption of strontium.
Actionable advice:
Strontium and any calcium-containing foods, drinks, or supplements should be separated by at least 4 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Saturable uptake of calcium is carrier mediated, since it is inhibited competitively by strontium and noncompetitively by magnesium.
Label source:
PubMed: Mineral and electrolyte metabolism (1990)
Source url:
Exact phrase from label:
Strontium present outside the vesicle inhibited saturable calcium uptake competitively, consistent with binding to the transporter at the same site as calcium.
Label source:
PubMed: The American journal of physiology (1989)
Source url:
Exact phrase from label:
When the calcium concentration was increased, the strontium passive absorption was decreased. The vitamin D3 and its derivatives increased intestinal strontium transport significantly and this increment was not modified by calcium. In our experiment, calcium is competitive with strontium only in passive absorption.
Label source:
PubMed: Comptes rendus des seances de la Societe de biologie et de ses filiales (1976)
Action type:
separate
Target id:
/intervention/calcium-citrate
Target name:
Calcium Supplements
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
Supplemental calcium directly competes with strontium for intestinal absorption, significantly lowering the amount of strontium that enters the bloodstream.
Actionable advice:
Strontium and calcium supplement doses should be separated by a minimum of 4 hours.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
Absorption of strontium from the gastrointestinal tract shares a common mechanism with absorption of calcium.
Label source:
Anecdotal: NCBI
Action type:
separate
Target id:
/dietary/meal
Target name:
Any Caloric Meal
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Food in the stomach, especially meals containing minerals like calcium, significantly impairs the absorption of strontium from the gut.
Actionable advice:
Strontium should be taken on a completely empty stomach, at least 2 hours before or 2 hours after eating.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Mean absolute bioavailability of strontium was 25% without a meal and 19% with a meal, whereas the intraindividual variation was 24% and 20%, respectively.
Label source:
PubMed: British journal of clinical pharmacology (1996)
Source url:
Exact phrase from label:
Absorption patterns are characteristically different for uptake from solutions or from whole meals.
Label source:
PubMed: Health physics (2006)
Source url:
Exact phrase from label:
The effect of food on strontium absorption was examined in a further 33 normal subjects (age 21-60 years), and the administration of the strontium with a standard breakfast was shown to reduce the variance at individual time points.
Label source:
PubMed: British medical journal (Clinical research ed.) (1987)
Action type:
separate
Target id:
/condition/renal-impairment
Target name:
Severe Renal Impairment
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Strontium is eliminated by the kidneys. In individuals with severely impaired kidney function (e.g., creatinine clearance <30 mL/min), strontium can accumulate to potentially toxic levels.
Actionable advice:
Strontium should be strictly avoided with severe kidney disease.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
The drugs/drug classes most commonly prescribed inappropriately were perindopril, fenofibrate, glibenclamide, gliptins, metformin, olmesartan, bisphosphonates and strontium.
Label source:
PubMed: Drugs & aging (2015)
Source url:
Exact phrase from label:
Patients with impaired renal function can accumulate strontium in the bone, which has been associated with the development of osteomalacia.
Label source:
PubMed: Kidney international (2005)
Source url:
Exact phrase from label:
Animal studies demonstrated that high doses of strontium induced alterations of mineralization and, in a rat model of chronic renal failure, high strontium doses induced mineralization defects, with a corresponding 160-fold accumulation of strontium in bone.
Label source:
PubMed: Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association (2002)
Action type:
avoid
Target id:
/condition/venous-thromboembolism
Target name:
History of Blood Clots (VTE)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Clinical trials with the prescription form, strontium ranelate, showed a small but significant increase in the risk of serious blood clots, such as deep vein thrombosis (DVT) and pulmonary embolism (PE).
Actionable advice:
Strontium should be strictly avoided with a personal or strong family history of blood clots.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
An association between strontium ranelate and venous thromboembolism (VTE) was identified in an analysis of phase III clinical trials.
Label source:
PubMed: Incidence of venous thromboembolism in users of strontium ranelate: an analysis of data from a prescription-event monitoring study in England. (PMID 20553059)
Action type:
avoid
Target id:
/condition/cardiovascular-disease
Target name:
Established Cardiovascular Disease
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Studies with strontium ranelate showed an increased risk of myocardial infarction (heart attack) in patients with established cardiovascular disease, uncontrolled hypertension, or other major cardiovascular risk factors.
Actionable advice:
Strontium should be avoided with a history of heart attack, stroke, peripheral artery disease, or uncontrolled high blood pressure.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Randomised controlled trial (RCT) data indicate a higher incidence of non-adjudicated myocardial infarction (MI) with strontium ranelate versus placebo (1.7 vs 1.1%; odds ratio [OR]: 1.6; 95% CI: 1.07 - 2.38; p = 0.020) (Mantel-Haenzel estimate of the OR). There was no increase in cardiovascular mortality.
Label source:
PubMed: Expert opinion on drug safety (2014)
Source url:
Exact phrase from label:
Strontium ranelate, under its current licence, thus provides a useful therapeutic option for severe osteoporosis in those who do not have cardiovascular risk factors.
Label source:
PubMed: Aging clinical and experimental research (2021)
Source url:
Exact phrase from label:
the increased risk of myocardial infarction with strontium was not identified in a pivotal phase 3 clinical trial despite specific regulatory review of cardiovascular events; data on myocardial infarction were not included in any primary publication
Label source:
PubMed: BMJ open (2014)
Action type:
avoid
Target id:
/condition/pregnancy
Target name:
Pregnancy
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
The safety of strontium during pregnancy is unknown; it can cross the placenta and may interfere with fetal bone development.
Actionable advice:
Strontium should be strictly avoided during pregnancy.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Source url:
Exact phrase from label:
Pregnancy: Based on animal data, may cause fetal harm (8.1)
Label source:
Anecdotal: DailyMed
Action type:
avoid
Target id:
/condition/lactation
Target name:
Breastfeeding (Lactation)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Strontium is excreted in breast milk, and its effects on a nursing infant's bone development are unknown and potentially harmful.
Actionable advice:
Strontium should be strictly avoided while breastfeeding.
Validation status:
unvalidatable
Evidence tier:
tier_e
Evidence basis:
unvalidatable
Evidence anchors:
Source url:
Scientific literature support not found
Exact phrase from label:
Label source:
Action type:
avoid
Target id:
/class/chelating-minerals
Target name:
Other Divalent Minerals (Mg, Zn, Fe)
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Divalent minerals like magnesium, zinc, and iron can compete with strontium for the same intestinal absorption channels, potentially reducing its bioavailability.
Actionable advice:
Strontium and magnesium, zinc, or iron supplements should be separated by at least 2 hours.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Chronic dietary deficiency since birth in Ca, Mg and Zn induced excessive absorption of divalent cations which accelerates oxidant-mediated neuronal degenerations in a genetically susceptible population.
Label source:
PubMed: [Disappearance of ALS from Guam: implications for exogenous causes] (PMID 8752460)
Action type:
separate
Target id:
/intervention/levothyroxine
Target name:
Levothyroxine
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
Similar to calcium, the strontium cation may bind to levothyroxine in the gut and reduce its absorption, potentially leading to decreased thyroid hormone efficacy. [class-derived from: class_pharmacology]
Actionable advice:
Doses of strontium and levothyroxine should be separated by at least 4 hours.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Inform patients that agents such as iron and calcium supplements and antacids can decrease the absorption of levothyroxine.
Label source:
FDA label: Levothyroxine (Synthroid)
Action type:
separate
Target id:
/intervention/bisphosphonates
Target name:
Bisphosphonates
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
12
Hours after target:
12
Description:
Both strontium and bisphosphonates require administration on an empty stomach for absorption and can interfere with each other's uptake if taken too closely together.
Actionable advice:
If taking both, take them on alternate days or separated by at least 12 hours.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
The drug release profiles were compared, and it was found that all Mg/Ca/Sr-containing compounds exhibit variable deceleration of the "active" CLOD release compared to the Na-containing reference.
Label source:
PubMed: Antiosteolytic Bisphosphonate Metallodrug Coordination Networks: Dissolution Profiles and In Vitro/In Vivo Toxicity toward Controlled Release. (PMID 41252551)
Action type:
separate
Target id:
/biomarker/bone-mineral-density
Target name:
Bone Mineral Density (DEXA Scan)
Severity:
moderate
Interaction type:
assay_interference
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Strontium is a heavier element than calcium; its incorporation into bone artificially inflates bone mineral density (BMD) measurements on DEXA scans, overestimating bone strength.
Actionable advice:
It is a good idea to let a doctor and the DEXA technician know about strontium use so results can be interpreted correctly.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Bone quantity, as determined by the current gold standard, dual energy X-ray absorptiometry (DXA), through measured areal bone mineral density (aBMD), is subject to positive biases if bone strontium levels are high.
Label source:
PubMed: Medical physics (2016)
Source url:
Exact phrase from label:
This study concludes that QUS can potentially be used for the determination of bone quality without introducing biases due to bone strontium levels as is known to be the case with DXA determined aBMD.
Label source:
PubMed: Medical physics (2016)
Source url:
Exact phrase from label:
Results confirm strontium administration increased bone tissue mineral density (TMD) and Sr content, with SrC exhibiting the weakest effect.
Label source:
PubMed: International journal of molecular sciences (2024)
Action type:
monitor
Target id:
/circadian/sleep
Target name:
Going to Sleep
Severity:
moderate
Interaction type:
synergistic
Nature:
temporal
Temporal spacing:
Hours before target:
0.5
Hours after target:
null
Description:
Taking strontium at bedtime typically ensures the longest possible fasting window away from food and other minerals, which is required to maximize its absorption.
Actionable advice:
A daily dose of strontium is best taken at bedtime, at least 2 hours after the last meal or supplement.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
To avoid this interaction, take antacids at least two hours after taking strontium products.
Label source:
Anecdotal: WebMD
Action type:
separate
Target id:
/biomarker/serum-calcium
Target name:
Serum Calcium Test
Severity:
minor
Interaction type:
assay_interference
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
High levels of strontium in the blood can interfere with certain colorimetric laboratory methods for measuring calcium, potentially causing a falsely elevated reading.
Actionable advice:
It is generally best to let a physician know about strontium use when they are interpreting serum calcium lab results.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Exogenous strontium addition to plasma caused positive bias for total calcium measurements. Strontium concentrations of 1.0 mg/dL (0.114 mmol/L), 2.5 mg/dL (0.284 mmol/L), and 5.0 mg/Dl (0.568 mmol/L) resulted in mean biases of 1.9% to 3.5%, 4.9% to 9.0%, and 10.8% to 19.2%, respectively, for total calcium measurement procedures.
Label source:
PubMed: The journal of applied laboratory medicine (2023)
Source url:
Exact phrase from label:
BACKGROUND: Bone health supplements containing strontium are available without prescription, however, the effects of strontium interference on clinical laboratory calcium measurement procedures are unknown.
Label source:
PubMed: The journal of applied laboratory medicine (2023)
Source url:
Exact phrase from label:
A colorimetric probe based on 2-mercaptosuccinic acid-functionalized gold nanoparticles has been developed to exhibit selectivity towards Ca(2+), Sr(2+), and Ba(2+) ions over other metallic cations under specified conditions and finds its practical application in detecting Ca(2+) levels in water.
Label source:
PubMed: The Analyst (2011)
Action type:
monitor