Preventive treatment of nephrolithiasis with alkali citrate—a critical review

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

2022 Recommendations of the AFU Lithiasis Committee: Medical management - from diagnosis to treatment

The morphological-compositional analysis of urinary stones allows distinguishing schematically several situations: dietary, digestive, metabolic/hormonal, infectious and genetic problems. Blood and urine testing are recommended in the first instance to identify risk factors of urinary stone disease in order to avoid recurrence or progression. The other objective is to detect a potential underlying pathology associated with high risk of urinary stone disease (e.g. primary hyperparathyroidism, primary or enteric hyperoxaluria, cystinuria, distal renal tubular acidosis) that may require specific management. Lifestyle-diet measures are the basis of the management of all stone types, but pharmacological treatments may be required. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU 2022] and their adaptability to the French context.

Lime juice as a dietary alternative to mist potassium citrate for urine alkalinisation: A prospective, cross-over clinical trial

INTRODUCTION

Urinary citrate is a potent inhibitor of urinary crystallization that is freely filtered in the proximal tubule of the kidney. We aimed to investigate the effect of citrate supplementation with fresh lime juice on the urinary pH and calcium excretion level among healthy individuals compared with that of mist potassium citrate.

METHOD

In this prospective, cross-over single-centre study, 50 healthy medical student volunteers were randomly allocated to two treatment arms. One arm was prescribed with potassium citrate, while the other arm received citrate supplementation with a home preparation of fresh lime juice. The urinary pH and calcium-to-creatinine ratio (uCa/uCr) were measured at baseline and after 7 days of treatment. This was followed by a washout period of 2 weeks, after which each participant crossed over to the other treatment arm, and the urinary measurements were repeated.

RESULTS

Potassium citrate significantly increased the urinary pH among all participants, while fresh lime juice did not. Both fresh lime juice and potassium citrate reduced the uCa/uCr, although this effect was not significant.

CONCLUSION

Fresh lime juice is not as effective as potassium citrate in improving the urinary pH and calcium excretion level of healthy individuals. Therefore, it should be used as an adjunct rather than an alternative to potassium citrate.

[Follow-up after urolithiasis management]

BACKGROUND

Urinary stones often affect younger people. Because the risk of recurrence is high, regular follow-up is important for individuals at risk.

OBJECTIVE

To summarize the extent of urinary stones and the health and economic impact in the population; to provide recommendations for general and stone-specific follow-up.

MATERIALS AND METHODS

Analysis and discussion of publications and guideline recommendations.

RESULTS

The risk of recurrence after a stone attack can be high depending on the risk profile. An initial metabolic workup should be performed promptly after stone therapy. General dietary management should be intensified by stone-specific dietary management depending on the risk profile. Nutritional counseling may be helpful. Imaging after stone therapy is used to monitor the success of treatment and detect recurrences early. Since the risk of recurrence can vary greatly depending on the stone composition, not only the type of imaging but also its frequency should be adjusted accordingly. The same applies to the various stone therapies, which help determine the frequency and type of imaging follow-up. Exact guidelines and cost-effectiveness analyses of follow-up examinations after stone therapy are unfortunately missing.

CONCLUSIONS

Acute urolithiasis represents an excruciating experience for patients. Accordingly, their willingness to undergo metaphylaxis and follow-up shortly after the event is strong. Since the risk of recurrence after a stone attack can be very high, regular follow-up after stone therapy is essential. The frequency of follow-up should be adapted to the probability of stone recurrence.

Causes and prevention of kidney stones: separating myth from fact

Despite high-level evidence supporting the use of pharmacotherapy therapy for the prevention of kidney stones, adherence to medications is often poor because of side-effects, inconvenience and cost. Furthermore, with a desire for more 'natural' products, patients seek dietary and herbal remedies over pharmacotherapy. However, patients are often unaware of the potential side-effects, lack of evidence and cost of these remedies. Therefore, in the present review we examine the evidence for a few of the commonly espoused non-prescription agents or dietary recommendations that are thought to prevent stone formation, including lemonade, fish oil (omega fatty acids), Phyllanthus niruri and the Dietary Approaches to Stop Hypertension (DASH) diet. While the present review includes only a few of the stone-modulating recommendations available to the lay community, we focussed on these four due to their prevalent use. Our goal is not to only dispel commonly held notions about stone disease, but also to highlight the lack of high-level evidence for many commonly utilised treatments.

Upregulation of the Renin-Angiotensin System Pathways and SARS-CoV-2 Infection: The Rationale for the Administration of Zinc-Chelating Agents in COVID-19 Patients

The article describes the rationale for the administration of zinc-chelating agents in COVID-19 patients. In a previous work I have highlighted that the binding of the SARS-CoV spike proteins to the zinc-metalloprotease ACE2 has been shown to induce ACE2 shedding by activating the zinc-metalloprotease ADAM17, which ultimately leads to systemic upregulation of ACE2 activity. Moreover, based on experimental models, it was also shown the detrimental effect of the excessive systemic activity of ACE2 through its downstream pathways, which leads to "clinical" manifestations resembling COVID-19. In this regard, strong upregulation of circulating ACE2 activity was recently reported in COVID-19 patients, thus supporting the previous hypothesis that COVID-19 may derive from upregulation of ACE2 activity. Based on this, a reasonable hypothesis of using inhibitors that curb the upregulation of both ACE2 and ADAM17 zinc-metalloprotease activities and consequent positive feedback-loops (initially triggered by SARS-CoV-2 and subsequently sustained independently on viral trigger) is proposed as therapy for COVID-19. In particular, zinc-chelating agents such as citrate and ethylenediaminetetraacetic acid (EDTA) alone or in combination are expected to act in protecting from COVID-19 at different levels thanks to their both anticoagulant properties and inhibitory activity on zinc-metalloproteases. Several arguments are presented in support of this hypothesis and based on the current knowledge of both beneficial/harmful effects and cost/effectiveness, the use of chelating agents in the prevention and therapy of COVID-19 is proposed. In this regard, clinical trials (currently absent) employing citrate/EDTA in COVID-19 are urgently needed in order to shed more light on the efficacy of zinc chelators against SARS-CoV-2 infection in vivo.

Hexametaphosphate as a potential therapy for the dissolution and prevention of kidney stones

The incidence of kidney stones is increasing worldwide, and recurrence is common (50% within 5 years). Citrate, the current gold standard therapy, which is usually given as potassium or sodium salts, is used because it raises urine pH and chelates calcium, the primary component of up to 94% of stones. In this study hexametaphosphate (HMP), a potent calcium chelator, was found to be 12 times more effective at dissolving calcium oxalate, the primary component of kidney stones, than citrate. HMP was also observed to be effective against other common kidney stone components, namely calcium phosphate and struvite (magnesium ammonium phosphate). Interestingly, HMP was capable of raising the zeta potential of calcium oxalate particles from -15.4 to -34.6 mV, which may prevent stone growth by aggregation, the most rapid growth mechanism, and thus avert occlusion. Notably, HMP was shown to be up to 16 times as effective as citrate at dissolving human kidney stones under simulated physiological conditions. It may thus be concluded that HMP is a promising potential therapy for calcium and struvite kidney stones.

Monosodium Glutamate (MSG) Renders Alkalinizing Properties and Its Urinary Metabolic Markers of MSG Consumption in Rats

Monosodium glutamate (MSG) is widely used as a flavor enhancer and its effects on human health are still debated. We aimed to investigate whether MSG can act as alkalinizing agent in murine models and if its metabolites are biomarkers of MSG consumption. For this purpose, adult male Wistar rats were given water added with 1 g% MSG or three types of control water, including sodium chloride (NaCl) and sodium bicarbonate (NaHCO₃). At 14 days, urinary pH, electrolytes, urinary metabolites and ion-exchanger gene expression were determined. The results revealed that MSG-treated rats had significantly more alkaline urine and higher levels of urinary sodium and bicarbonate similar to NaHCO₃ controls. These changes correlated with a lower expression of ion-exchanger genes, namely, CAII, NBC1, and AE1, which are involved in bicarbonate kidney reabsorption. The urinary metabolic profiles also revealed similar patterns for the MSG and NaHCO₃ groups. In conclusion, MSG exhibits similar properties to NaHCO₃, an alkalinizing agent, with regard to inducing alkaline urine, reducing bicarbonate kidney reabsorption, and generating a specific urinary metabolic pattern. We believe that these observations will be useful to further study the MSG effects in humans.

Coconut Water: An Unexpected Source of Urinary Citrate

Purpose

Coconut water has long been touted for its medicinal qualities including natural hydration. We sought to determine whether its consumption would induce changes to urinary lithogenic factors beyond changes in urine volume.

Materials and Methods

After Institutional Review Board approval, volunteers with no prior history of nephrolithiasis were recruited. Each participant was randomized initially to either the coconut water or the water phase of the study. Participants kept meticulous food and fluid intake logs during the first phase of the study and were asked to replicate that diet for the second phase. For each phase the participant consumed 2L of either Taste of Nirvana® pure coconut water or tap water daily for four days. Participants were not restricted to consume additional fluid of their choice during their assigned study phase. During days 3 and 4 of each phase the participant collected a 24-hour urine specimen. Coconut water citrate and malate content were measured and were used along with the beverage pH to calculate the total alkali content of the coconut water. Supersaturation levels were calculated using Equil2. Nonparametric paired analysis using the Wilcoxon test was performed for statistical analysis.

Results

There were 4 adult male and 4 adult female participants. Each individual's 24-hour urine collection had a creatinine excretion within 20% of the mean for each subject's four samples corroborating that all samples were collected properly. The two samples from each phase for each individual were averaged. The coconut water itself was also analyzed and it was calculated to have a total alkali content of 13.8 mEq/L. Consumption of coconut water significantly increased urinary citrate (29%, p=0.02), urinary potassium (130%, p=0.01), and urinary chloride (37%, p=0.03), without affecting urine pH (p=0.16) or volume beyond that of tap water (p=1.00).

Conclusions

Coconut water consumption increases urinary potassium, chloride, and citrate in nonstone forming individuals.

Protective Effects of Pistacia lentiscus L. fruit extract against calcium oxalate monohydrate induced proximal tubular injury

ETHNOPHARMACOLOGICAL RELEVANCE

The world prevalence of kidney stones is increasing and plants are frequently used to treat urolithiasis. Pistacia lentiscus L, a plant which freely grows around the Mediterranean basin areas, is widely used for various pathologies. P. lentiscus has an important impact as it has economical value on top of its pharmacological interest. Decoctions of its aerial parts and/or resin are used to treat kidney stones.

AIM OF THE STUDY

To in vitro assess the potential nephroprotective effect of Pistacia lentiscus ethanolic fruit extract (PLEF) on proximal tubular cells in response to the adhesion of calcium oxalate monohydrate (COM) crystals.

MATERIALS AND METHODS

Human Kidney [HK]-2 cells were incubated with and without COM in the presence or absence of PLEF. Cell viability was measured by the resazurin assay. The expression of E-cadherin was analyzed by PCR. The extracellular production of H₂O₂ was measured by Amplex® Red H₂O₂ Assay. The numbers of detached or non-adherent COM crystals in the presence of PLEF were microscopically captured and counted using ImageJ software. The interaction of PLEF with COM and the effect of PLEF on crystal size were analyzed by flow cytometry. The spectrophotometric measurement of turbidity was performed for assessing the COM concentration.

RESULTS

PLEF incubated with COM was able to increase the cell viability. The decrease of E-cadherin expression after incubation with COM was counteracted by PLEF. Overproduction of H₂O₂ induced by COM was also inhibited by PLEF. Observations using flow cytometry showed that interactions between PLEF and the COM crystals occurred. PLEF was also effective in reducing the particles size and in lowering COM concentration.

CONCLUSION

Our data show that COM tubulotoxicity can be significantly reversed by PLEF -at least in part- via an inhibition of COM crystals adhesion onto the apical membrane. This early beneficial effect of PLEF needs to be further investigated as a useful strategy in nephrolithiasis prevention.

[S2k guidelines on diagnostics, therapy and metaphylaxis of urolithiasis (AWMF 043/025) : Compendium]

Every tenth German citizen will suffer from at least one urinary calculus during the lifetime. The diagnostics, treatment and follow-up treatment of urolithiasis are, therefore, part of the daily routine practice for all urologists in hospitals and private practices as well as in many other disciplines, such as general practitioners, internists, nephrologists and pediatricians. Although the diagnostics and therapy have experienced substantial alterations over the last 10 years, the possibilities of metabolic diagnostics and secondary prevention for patients at risk are, unfortunately and unjustly, in many places very poorly represented. The present S2k guidelines, which for the first time were established in an interdisciplinary consensus process, represent the current practical recommendations and, whenever possible, use tables and algorithms in order to facilitate easy reference in the routine daily work. Last but not least, this greatly simplifies the measures for metaphylaxis.

Evaluating the effectiveness of adding magnesium chloride to conventional protocol of citrate alkali therapy on kidney stone size

BACKGROUND

Potassium citrate (K-Cit) is one of the therapeutic solutions broadly used in patients with urolithiasis. However, recent studies have shown that it is not so effective. Therefore, the goal of our study was to evaluate the effect of a combination of K-Cit - MgCl₂ oral supplements, on urinary stone size.

MATERIALS AND METHODS

This study was performed on 70 asymptomatic urolithiasis cases. The supplements included K-Cit and magnesium chloride (MgCl₂), purchased from (Merck Company, Germany). The patients were randomly divided into two groups. The urinary stone size was measured in the control group after prescribing K-Cit alone and the treated group with combination of K-Cit and MgCl₂ for 4 weeks by ultrasonography and also urinary parameter was measured in each groups.

RESULTS

The mean age of patients was 16.26 ± 5.70 years. Hyperoxaluria and hypercalciuria were seen in 70% and 52% of patients, respectively. Initially, the mean urinary stone size was measured in each groups and there is not any significant different. However, we find a significant decrease in urinary stone size in group which is treated with combination of K-Cit and MgCl₂ for 4 weeks in comparison with control group treated with K-Cit alone in the same duration of therapeutic course (5.1 ± 0.8 vs. 2.5 ± 1.2, P < 0.05). All ultrasonography were performed by one radiologist and device.

CONCLUSION

Our results suggested that a combination of K-Cit and MgCl₂ chloride is more effective on decreasing urinary stone size than K-Cit alone.

Alteration in Oxidative/nitrosative imbalance, histochemical expression of osteopontin and antiurolithiatic efficacy of Xanthium strumarium (L.) in ethylene glycol induced urolithiasis

Xanthium strumarium has traditionally been used in the treatment of urolitiasis especially by the rural people in India, but its antiurolithiatic efficacy was not explored scientifically till now. Therefore, the present study was designed to validate the ethnic practice scientifically, and explore the possible antiurolithiatic effect to rationalize its medicinal use. Urolitiasis was induced in hyperoxaluric rat model by giving 0.75% ethylene glycol (EG) for 28days along with 1% ammonium chloride (AC) for first 14days. Antiurolithiatic effect of aqueous-ethanol extract of Xanthium strumarium bur (xanthium) was evaluated based on urine and serum biochemistry, oxidative/nitrosative stress indices, histopathology, kidney calcium and calcium oxalate content and immunohistochemical expression of matrix glycoprotein, osteopontin (OPN). Administration of EG and AC resulted in hyperoxaluria, crystalluria, hypocalciuria, polyurea, raised serum urea, creatinine, erythrocytic lipid peroxidise and nitric oxide, kidney calcium content as well as crystal deposition in kidney section in lithiatic group rats. However, xanthium treatment significantly restored the impairment in above kidney function test as that of standard treatment, cystone. The up-regulation of OPN was also significantly decreased after xanthium treatment. The present findings demonstrate the curative efficacy of xanthium in ethylene glycol induced urolithiasis, possibly mediated through inhibition of various pathways involved in renal calcium oxalate formation, antioxidant property and down regulation of matrix glycoprotein, OPN. Therefore, future studies may be established to evaluate its efficacy and safety for clinical use.

Renal stone clinic survey: calcium stone formers' self-declared understanding of and adherence to physician's recommendations

Nothing is known about how well stone formers understand physician's explanations of stone formation, and a few data are available on adherence to provided recommendations. In this study, two groups of recurrent calcium stone formers (RCSFs) were compared. Group 1: 153 consecutive RCSF (118 men, 35 women) referred 1/2011-6/2014. At least 3 months after a 60-75 min consultation explaining metabolic evaluation and therapeutic measures, RCSF received a questionnaire by mail, regarding understanding of stone formation and adherence to therapeutic recommendations (diet, lifestyle, drug treatment). Response rate was 62 %. Group 2 (control): 81 consecutive RCSFs referred 7/2014-3/2016 (60 men, 21 women) were asked to answer the same questionnaire in the stone center while waiting for their follow-up consultation 3 months after starting prevention; response rate was 100 %. Alkali citrate was prescribed in 45 %. Answer sheets were analyzed anonymously, and frequencies of answers were compared by Chi-square test.

RESULTS

67 % (group 1) and 62 % (group 2) indicated >80 % understanding of the given information (NS). Over 80 % adherence to recommendations occurred in 26 and 30 % (NS). Most frequent changes in dietary/lifestyle habits were increases in calcium (93 vs. 89 %) and fluid intakes (81 vs. 78 %); lowering psychosocial stress (23 vs. 24 %) was least popular. Adherence to 100 % on 6-7 days/week was significantly more frequent for medication than for dietary/lifestyle interventions, both in group 1 (84 vs. 24 %, p < 0.001) and group 2 (91 vs. 28 %, p < 0.001).

CONCLUSIONS

(1) results do not differ whether RCSFs are voluntarily participating by mail or asked to answer questionnaires in the stone clinic; (2) pathophysiologic explanations of stone disease are understood to >80 % by 2/3 of RCSFs; (3) after 3 months, perfect adherence to recommended treatment is more frequent on alkali citrate than on dietary/lifestyle measures; and (4) increasing calcium and fluid intake are the most popular dietary measures.

Citrate salts for preventing and treating calcium containing kidney stones in adults

BACKGROUND

Kidney stones affect people worldwide and have a high rate of recurrence even with treatment. Recurrences are particularly prevalent in people with low urinary citrate levels. These people have a higher incidence of calcium phosphate and calcium oxalate stones. Oral citrate therapy increases the urinary citrate levels, which in turn binds with calcium and inhibits the crystallisation thus reduces stone formation. Despite the widespread use of oral citrate therapy for prevention and treatment of calcium oxalate stones, the evidence to support its clinical efficacy remains uncertain.

OBJECTIVES

The objective of this review was to determine the efficacy and adverse events associated with citrate salts for the treatment and prevention of calcium containing kidney stones.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 29 July 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that assessed the efficacy and adverse events associated with citrate salts for the treatment and prevention of calcium containing kidney stones in adults treated for a minimum of six months.

DATA COLLECTION AND ANALYSIS

Two authors assessed studies for inclusion in this review. Data were extracted according to predetermined criteria. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes.

MAIN RESULTS

We included seven studies that included a total of 477 participants, most of whom had oxalate stones. Of these, three studies (247 participants) compared potassium citrate with placebo or no intervention; three (166 participants) compared potassium-sodium citrate with no intervention; and one (64 participants) compared potassium-magnesium citrate with placebo. Overall, quality of the reporting of the included studies was considered moderate to poor, and there was a high risk of attrition bias in two studies.Compared with placebo or no intervention, citrate therapy significantly reduced the stone size (4 studies, 160 participants: RR 2.35, 95% CI 1.36 to 4.05). New stone formation was significantly lower with citrate therapy compared to control (7 studies, 324 participants: RR 0.26, 95% CI 0.10 to 0.68). The beneficial effect on stone size stability was also evident (4 studies, 160 participants: RR 1.97, 95% CI 1.19 to 3.26). Adverse events were reported in four studies, with the main side effects being upper gastrointestinal disturbance and one patient reported a rash. There were more gastrointestinal adverse events in the citrate group; however this was not significant (4 studies, 271 participants: RR 2.55, 95% CI 0.71 to 9.16). There were significantly more dropouts due to adverse events with citrate therapy compared to control (4 studies, 271 participants: RR 4.45, 95% CI 1.28 to 15.50). The need for retreatment was significantly less with citrate therapy compared to control (2 studies, 157 participants: RR 0.22, 95% CI 0.06 to 0.89).

AUTHORS' CONCLUSIONS

Citrate salts prevent new stone formation and reduce further stone growth in patients with residual stones that predominantly contain oxalate. The quality of reported literature remains moderate to poor; hence a well-designed statistically powered multi-centre RCT is needed in order to answer relevant questions concerning the efficacy of citrate salts.

[Urinary stones and bowel diseases: Systematic review]

PURPOSE

The aim of the study was to explain the relationship between urinary stones and bowel disease.

METHODS

A systematic review was performed on Medline, Embase and Cochrane using following keywords: urinary stones; urolithiasis; bowel; enteric and digestive. The literature selection was based on evidence and practical considerations.

RESULTS

Fifty-three articles were selected. Three types of urolthiasis are mainly involved in digestive pathologies: calcium oxalate stones, uric acid and ammonium acid urate stones. Bowel pathologies responsible for stone disease are divided into small bowel diseases, colonic lesions and lack of an oxalate degrading bacteria (Oxalobacter formigenes) in the intestinal flora. Resulting in a decreased urine output, pH, hyperoxaluria, hypocitraturia or a hypomagnesurie. Blood and urinary explorations are the basis of diagnostic management.

CONCLUSION

Bowel diseases can be responsible for urolthiasis. Understanding of the mechanisms, and metabolic evaluations can prevent recurrences. Increase fluid intake associated with specific supplementation and diet are the key of the treatment.

Citrate modulates lipopolysaccharide-induced monocyte inflammatory responses

Citrate, a central component of cellular metabolism, is a widely used anti-coagulant due to its ability to chelate calcium. Adenosine triphosphate (ATP)-citrate lyase, which metabolizes citrate, has been shown to be essential for inflammation, but the ability of exogenous citrate to impact inflammatory signalling cascades remains largely unknown. We hypothesized that citrate would modulate inflammatory responses as both a cellular metabolite and calcium chelator, and tested this hypothesis by determining how clinically relevant levels of citrate modulate monocyte proinflammatory responses to lipopolysaccharide (LPS) in a human acute monocytic leukaemia cell line (THP-1). In normal medium (0.4 mM calcium), citrate inhibited LPS-induced tumour necrosis factor (TNF)-α and interleukin (IL)-8 transcripts, whereas in medium supplemented with calcium (1.4 mM), TNF-α and IL-8 levels increased and appeared independent of calcium chelation. Using an IL-8-luciferase plasmid construct, the same increased response was observed in the activation of the IL-8 promoter region, suggesting transcriptional regulation. Tricarballylic acid, an inhibitor of ATP-citrate lyase, blocked the ability of citrate to augment TNF-α, linking citrate's augmentation effect with its metabolism by ATP-citrate lyase. In the presence of citrate, increased histone acetylation was observed in the TNF-α and IL-8 promoter regions of THP-1 cells. We observed that citrate can both augment and inhibit proinflammatory cytokine production via modulation of inflammatory gene transactivation. These findings suggest that citrate anti-coagulation may alter immune function through complex interactions with the inflammatory response.

Enteric hyperoxaluria secondary to small bowel resection: use of computer simulation to characterize urinary risk factors for stone formation and assess potential treatment protocols

BACKGROUND AND PURPOSE

We used computer modeling to investigate the influence of physicochemical stone risk factors on urinary supersaturation (SS) of calcium oxalate (CaOx) in patients with severe hyperoxaluria, relative hypocalciuria, hypocitraturia, and CaOx nephrolithiasis after extensive small bowel resection, usually performed for Crohn's disease. We also simulated different treatment strategies, including oral calcium supplements and citrate, in such patients.

MATERIALS AND METHODS

A baseline urine model was derived by consolidating data acquired by ourselves with those from another patient cohort. Calcium and oxalate excretions in this model were altered to obtain an extreme case. For comparison, additional models were based on published urine data from normal subjects (N) and idiopathic CaOx stone formers (SF). The Joint Expert Speciation System was used to simulate different urine situations based on reported compositional values.

RESULTS

[Ca(2+)][Ox(2-)] ionic concentration products and SS(CaOx) are substantially higher in enteric hyperoxaluric patients than in N and SF, despite their relatively lower calcium excretions. Molar Ca:Ox ratios are substantially lower in enteric hyperoxalurics than in N and SF. Oral calcium supplements can reduce SS(CaOx), but monitoring is required to avoid exceeding a safe dosing threshold. A simple calculation can alert the clinician that this threshold is being approached or even exceeded. Increasing urinary pH and citrate decreases SS(CaOx) but not to the same extent as decreasing Ox excretion.

CONCLUSIONS

Calcium supplements can help reduce stone risk in patients with severe enteric hyperoxaluria, but initial efforts should be directed toward reducing urinary oxalate by reducing dietary oxalate. Citrate therapy that increases both urine pH and urinary citrate provides an additional therapeutic benefit.

[Nephrolithiasis: metabolic defects and terapeutic implications]

Over the past 10 years, major progress has been made in the knowledge of urinary lithogenesis, including the potential pathogenetic role of Randall's plaques and renal tubular crystal retention. Urine supersaturation is the driving force of this process and can be induced by some risk factors, including low urine volume, high urinary excretion of calcium oxalate and uric acid and low urinary excretion of citrate. Primary hypercalciuria can be due to intestinal overabsorption renal leak and bone reabsorption of calcium. Prophilaxis is mainly conducted with thiazides and low calcium diet which is indicated only in the intestinal form. Primary hyperoxaluria is treated with pyridoxine and may require in the severe forms simultaneous renal and liver transplantation. Enteric hyperoxaluria is secondary to fatty acids malabsorption and requires diet, oral calcium and cholestiramine. Hyperuricosuria is caused by diet endogenous overproduction, mainly due to enzymatic defects or high renal excretion of uric acid. Urine alkalinization with K or K and Mg citrate can prevent stone formation even in idiopathic uric acid nephrolithiasis, in which a defect of urine acidification is supposed to be the main abnormality, and in hypocitraturic patients. Cystinuria is a rare inherited defect with an intense clinical impact. It can be classified in three forms and urinary stone formation is the role. Increased solubility and conversion of cystine in a more soluble form are the main goals of the prophylaxis which includes K citrate and thiol agents administration. Tiopronin is preferred to D-penicillamine due to its lower side effects.

Malic acid supplementation increases urinary citrate excretion and urinary pH: implications for the potential treatment of calcium oxalate stone disease

BACKGROUND AND PURPOSE

Raising urinary pH and citrate excretion with alkali citrate therapy has been a widely used treatment in calcium nephrolithiasis. Citrate lowers ionized Ca(+2) concentrations and inhibits calcium salt precipitation. Conservative alternatives containing citrate such as fruit juices have been investigated and recommended. Any compound that induces systemic alkalosis will increase citraturia. Malate, a polycarboxylic anion like citrate, is a potential candidate for chelating Ca(+2) and for inducing systemic alkalinization. We undertook to investigate these possibilities.

MATERIALS AND METHODS

Theoretical modeling of malic acid's effects on urinary Ca(+2) concentration and supersaturation (SS) of calcium salts was achieved using the speciation program JESS. Malic acid (1200 mg/day) was ingested for 7 days by eight healthy subjects. Urines (24 hours) were collected at baseline and on day 7. They were analyzed for routine lithogenic components, including pH and citrate. Chemical speciation and SS were calculated in both urines.

RESULTS

Modeling showed that complexation between calcium and malate at physiological concentrations of the latter would have no effect on SS. Administration of the supplement induced statistically significant increases in pH and citraturia. The calculated concentration of Ca(+2) and concomitant SS calcium oxalate (CaOx) decreased after supplementation, but these were not statistically significant. SS for the calcium phosphate salts hydroxyapatite and tricalcium phosphate increased significantly as a consequence of the elevation in pH, but values for brushite and octacalcium phosphate did not change significantly.

CONCLUSIONS

We speculate that consumption of malic acid induced systemic alkalinization leading to reduced renal tubular reabsorption and metabolism of citrate, and an increase in excretion of the latter. The decrease in SS(CaOx) was caused by enhanced complexation of Ca(+2) by citrate. We conclude that malic acid supplementation may be useful for conservative treatment of calcium renal stone disease by virtue of its capacity to induce these effects.

Citrate occurs widely in healthy and pathological apatitic biomineral: mineralized articular cartilage, and intimal atherosclerotic plaque and apatitic kidney stones

There is continuing debate about whether abundant citrate plays an active role in biomineralization of bone. Using solid state NMR dipolar dephasing, we examined another normally mineralized hard tissue, mineralized articular cartilage, as well as biocalcifications arising in pathological conditions, mineralized intimal atherosclerotic vascular plaque, and apatitic uroliths (urinary stones). Residual nondephasing ¹³C NMR signal at 76 ppm in the spectra of mineralized cartilage and vascular plaque indicates that a quaternary carbon atom resonates at this frequency, consistent with the presence of citrate. The presence, and as yet unproven possible mechanistic involvement, of citrate in tissue mineralization extends the compositional, structural, biogenetic, and cytological similarities between these tissues and bone itself. Out of 10 apatitic kidney stones, five contained NMR-detectable citrate. Finding citrate in a high proportion of uroliths may be significant in view of the use of citrate in urolithiasis therapy and prophylaxis. Citrate may be essential for normal biomineralization (e.g., of cartilage), play a modulatory role in vascular calcification which could be a target for therapeutic intervention, and drive the formation of apatitic rather than other calcific uroliths, including more therapeutically intractable forms of calcium phosphate.

Aluminum citrate blocks toxicity of calcium oxalate crystals by preventing binding with cell membrane phospholipids

BACKGROUND/AIMS

Renal damage from ethylene glycol and primary hyperoxaluria is linked to accumulation of calcium oxalate monohydrate (COM) crystals in the renal proximal tubule (PT). In vitro studies have shown that aluminum citrate (AC), uniquely among citrate salts, blocks COM cytotoxicity to tubular cells. These studies were designed to evaluate the interaction of COM with membrane phospholipids and the ability of AC to reduce COM toxicity by interfering with this interaction.

METHODS

Interaction of COM with phospholipids was assessed using differential scanning calorimetric analysis of structural changes in specific liposomes. Interaction of COM with cell membranes was studied by measuring binding of radiolabeled crystals by human PT (HPT) cells.

RESULTS

Analysis of liposomes prepared from phosphatidylserine (PS) or phosphatidylcholine (PC) showed that COM interfered with the gel-liquid transition of PS liposomes, but not that of PC liposomes. AC reversed the COM-induced changes in liposomal structure. AC inhibited the binding of [(14)C]-COM by HPT cells in a concentration-dependent manner. AC blocked COM binding by interacting with the crystal surface and not the cell membrane.

CONCLUSION

These results indicate that AC blocks the binding of COM by PT cells, and consequently its cytotoxicity, by attaching to the surface of the crystal. Thus, AC, or a related compound that works by the same mechanism, could be a useful adjunct therapy to reduce the renal damage produced by severe hyperoxaluria.

Aluminum citrate prevents renal injury from calcium oxalate crystal deposition

Calcium oxalate monohydrate crystals are responsible for the kidney injury associated with exposure to ethylene glycol or severe hyperoxaluria. Current treatment strategies target the formation of calcium oxalate but not its interaction with kidney tissue. Because aluminum citrate blocks calcium oxalate binding and toxicity in human kidney cells, it may provide a different therapeutic approach to calcium oxalate-induced injury. Here, we tested the effects of aluminum citrate and sodium citrate in a Wistar rat model of acute high-dose ethylene glycol exposure. Aluminum citrate, but not sodium citrate, attenuated increases in urea nitrogen, creatinine, and the ratio of kidney to body weight in ethylene glycol-treated rats. Compared with ethylene glycol alone, the addition of aluminum citrate significantly increased the urinary excretion of both crystalline calcium and crystalline oxalate and decreased the deposition of crystals in renal tissue. In vitro, aluminum citrate interacted directly with oxalate crystals to inhibit their uptake by proximal tubule cells. These results suggest that treating with aluminum citrate attenuates renal injury in rats with severe ethylene glycol toxicity, apparently by inhibiting calcium oxalate's interaction with, and retention by, the kidney epithelium.

Alkaline citrate reduces stone recurrence and regrowth after shockwave lithotripsy and percutaneous nephrolithotomy

OBJECTIVE

To evaluate the preventive effects of alkaline citrate on stone recurrence as well as stone growth post-ESWL or PCNL in patients with calcium-containing stones.

MATERIALS AND METHODS

A total of 76 patients with calcium calculi who were stone-free or had residual stones less than 4 mm following ESWL and PCNL were enrolled. All patients were independently randomized into two groups. The treated group (N = 39) was given 81 mEq per day of oral potassium-sodium citrate (27 mEq three times a day), and the untreated group (N = 37) serving as controls. Blood, twenty-four hour urine analysis, and plain KUB were measured and compared at the baseline and after 12 months.

RESULTS

At baseline, hypocitraturia was found in 20 of 39 patients (46.05%) of Group I and 15 of 37 patients (40.5%) of Group II. At 12 months, hypocitraturia was found in 3 of 39 (7.69%) and 14 of 37 (37.83%) of Group I and Group II, respectively (p = 0.007). At the 12 month follow-up, of the stone-free group, 92.3% of the treated group and 57.7% of the control group were still stone free. Of the residual stone group, 30.8% and 9.1% of treated and control group were stone-free, respectively. The increased stone size found in 7.7%) and 54.5%) of treated and control groups, respectively.

CONCLUSION

Sodium-potassium citrate provides positive effects on stone-forming activities in calcium stone patients suffering from urolithiasis following treatment with ESWL and PCNL procedures at the 12-month follow-up.

Studies on the in vitro and in vivo antiurolithic activity of Holarrhena antidysenterica

Holarrhena antidysenterica has a traditional use in the treatment of urolithiasis, therefore, its crude extract has been investigated for possible antiurolithic effect. The crude aqueous-methanolic extract of Holarrhena antidysenterica (Ha.Cr) was studied using the in vitro and in vivo methods. In the in vitro experiments, Ha.Cr demonstrated a concentration-dependent (0.25-4 mg/ml) inhibitory effect on the slope of aggregation. It decreased the size of crystals and transformed the calcium oxalate monohydrate (COM) to calcium oxalate dehydrate (COD) crystals, in calcium oxalate metastable solutions. It also showed concentration-dependent antioxidant effect against 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals and lipid peroxidation induced in rat kidney tissue homogenate. Ha.Cr (0.3 mg/ml) reduced (p < 0.05) the cell toxicity and LDH release in renal epithelial cells (MDCK) exposed to oxalate (0.5 mM) and COM (66 μg/cm(2)) crystals. In male Wistar rats, receiving 0.75 % ethylene glycol (EG) for 21 days along with 1 % ammonium chloride (AC) in drinking water, Ha.Cr treatment (30-100 mg/kg) prevented the toxic changes caused by lithogenic agents; EG and AC, like loss of body weight, polyurea, oxaluria, raised serum urea and creatinine levels and crystal deposition in kidneys compared to their respective controls. These data indicate that Holarrhena antidysenterica possesses antiurolithic activity, possibly mediated through the inhibition of CaOx crystal aggregation, antioxidant and renal epithelial cell protective activities and may provide base for designing future studies to establish its efficacy and safety for clinical use.

Urinary stone formers with hypocitraturia and 'normal' urinary pH are at high risk for recurrence

BACKGROUND

Citrate is one of the most important inhibitors in urolithiasis. Hypocitraturia is a common risk factor in stone formers. Citrate excretion is regulated - amongst others - by acidosis and protein intake. A considerable number of stone formers, however, show hypocitraturia in the presence of normal urine pH levels. This is potentially due to defects in the renal tubular citrate carriers (NaDC 1 and 3) which may be genetically determined.

PATIENTS AND METHODS

350 consecutive stone formers were examined. Exclusion criteria were urinary tract infection, hypokalemia, and steatorrhea. The following parameters were measured: serum: creatinine, calcium, potassium, and uric acid; urine: pH profiles, citrate, calcium, uric acid, ammonia, urea, and creatinine.

RESULTS

83/350 patients were hypocitraturic (48 males, 35 females). 14/83 had low urine pH (≤ 6), 69/83 showed normal levels (>6). In the latter group there was a significantly higher recurrence rate (23 vs. 9%). The two groups were not different in serum parameters apart from uric acid. In urine, only pH and calcium (males) were significantly lower in the first group. Citrate did not correlate with urine pH and creatinine in the hypocitraturia-normal pH group, only with calcium in both sexes and urea and ammonia in females. In the hypocitraturia-low pH patients, there was no significant correlation between citrate and any other parameter tested.

CONCLUSIONS

Hypocitraturia with normal urine pH is an entity indicating a high risk for recurrence. Since there was no correlation between citrate and pH, urea and ammonia, respectively, citrate excretion is not regulated in these patients as usual. There may be a link to calcium excretion. Potentially, these patients have defects in the renal tubular citrate carriers which may be genetically determined. Genetic examinations should be performed to elucidate a potential genetic disorder in hypocitraturia-normal pH stone formers.

Matrix Gla protein inhibits ectopic calcification by a direct interaction with hydroxyapatite crystals

Mice lacking the gene encoding matrix gla protein (MGP) exhibit massive mineral deposition in blood vessels and die soon after birth. We hypothesize that MGP prevents arterial calcification by adsorbing to growing hydroxyapatite (HA) crystals. To test this, we have used a combined experimental-computational approach. We synthesized peptides covering the entire sequence of human MGP, which contains three sites of serine phosphorylation and five sites of γ-carboxylation, and studied their effects on HA crystal growth using a constant-composition autotitration assay. In parallel studies, the interactions of these sequences with the {100} and {001} faces of HA were analyzed using atomistic molecular dynamics (MD) simulations. YGlapS (amino acids 1-14 of human MGP) and SK-Gla (MGP43-56) adsorbed rapidly to the {100} and {001} faces and strongly inhibited HA growth (IC(50) = 2.96 μg/mL and 4.96 μg/mL, respectively). QR-Gla (MGP29-42) adsorbed more slowly and was a moderate growth inhibitor, while the remaining three (nonpost-translationally modified) peptides had little or no effect in either analysis. Substitution of gla with glutamic acid reduced the adsorption and inhibition activities of SK-Gla and (to a lesser extent) QR-Gla but not YGlapS; substitution of phosphoserine with serine reduced the inhibitory potency of YGlapS. These studies suggest that MGP prevents arterial calcification by a direct interaction with HA crystals that involves both phosphate groups and gla residues of the protein. The strong correlation between simulated adsorption and measured growth inhibition indicates that MD provides a powerful tool to predict the effects of proteins and peptides on crystal formation.

Antiurolithic activity of Origanum vulgare is mediated through multiple pathways

Background

Origanum vulgare Linn has traditionally been used in the treatment of urolithiasis. Therefore, we investigated the crude extract of Origanum vulgare for possible antiurolithic effect, to rationalize its medicinal use.

Methods

The crude aqueous-methanolic extract of Origanum vulgare (Ov.Cr) was studied using the in vitro and in vivo methods. In the in vitro experiments, supersaturated solution of calcium and oxalate, kidney epithelial cell lines (MDCK) and urinary bladder of rabbits were used, whereas, in the in vivo studies, rat model of urolithiasis was used for the study of preventive and curative effect.

Results

In the in vitro experiments, Ov.Cr exhibited a concentration-dependent (0.25-4 mg/ml) inhibitory effect on the slope of nucleation and aggregation and also decreased the number of calcium oxalate monohydrate crystals (COM) produced in calcium oxalate metastable solutions. It also showed concentration-dependent antioxidant effect against DPPH free radical and lipid peroxidation induced in rat kidney tissue homogenate. Ov.Cr reduced the cell toxicity using MTT assay and LDH release in renal epithelial cells (MDCK) exposed to oxalate (0.5 mM) and COM (66 μg/cm²) crystals. Ov.Cr relaxed high K⁺ (80 mM) induced contraction in rabbit urinary bladder strips, and shifted the calcium concentration-response curves (CRCs) towards right with suppression of the maximum response similar to that of verapamil, a standard calcium channel blocker. In male Wistar rats receiving lithogenic treatment comprising of 0.75% ethylene glycol in drinking water given for 3 weeks along with ammonium chloride (NH₄Cl) for the first 5 days, Ov.Cr treatment (10-30 mg/kg) prevented as well as reversed toxic changes including loss of body weight, polyurea, crystalluria, oxaluria, raised serum urea and creatinine levels and crystal deposition in kidneys compared to their respective controls.

Conclusion

These data indicating the antiurolithic activity in Ov.Cr, possibly mediated through inhibition of CaOx crystallization, antioxidant, renal epithelial cell protective and antispasmodic activities, rationalizes its medicinal use in urolithiasis.

Prospective randomized clinical trial comparing phytotherapy with potassium citrate in management of minimal burden (≤8 mm) nephrolithiasis

AIM

To compare efficacy and tolerability of phytotherapy (PT) vs. potassium citrate (KC) in patients with minimal nephrolithiasis. To compare and assess changes in value of certain serum (Ca(2)+, PO(4) (3-), uric acid [UA]) and urinary (24-hr Ca(2+), PO(4) (3-), UA, citrate, oxalate, and urine pH) parameters in patients being treated with PT or KC.

MATERIALS AND METHODS

After clearance by the local institutional ethics committee, 60 patients of nephrolithiasis who had consented for the study, were enrolled (as per entry criteria) and randomized into citrate therapy (group-I) or PT (group-II). PT was administered as a nutritional supplement, using a lupeol-based extract (Tablet Calcury™, two tablets twice a day). They were monitored for the changes in the serum and urinary biochemical, radiological, and clinical parameters (efficacy and tolerability) as per protocol.

RESULTS

Group-I patients demonstrated favorable changes in certain biochemical parameters (decreased serum calcium, urinary UA/oxalate, increased urinary citrate and pH) along with significant symptomatic improvement (decrease in visual analogue pain score with increased stone clearance/reduction in stone size). Four (13.3%) patients of group-I had mild upper gastrointestinal discomfort which was controlled with antacids. Group-II patients had favorable changes in biochemical parameters (decreased serum UA and increased urinary citrate) along with significant symptomatic improvement (reduction/clearance in the stone size), but without any noticeable side effects.

CONCLUSIONS

Medical therapies with both KC and PT (with lupeol extract using Calcury™) were effective in reducing the stone size and symptoms of nephrolithiasis. It appeared that KC was biochemically efficacious in producing some favorable biochemical changes with some side effects, whereas PT was probably clinically efficacious in hastening stone expulsion (<8 mm) without any observed adverse events. Although both the medical therapies were not effective in all aspects, we believe that PT using lupeol-based extract (Calcury™) may be used as an alternative form of medical therapy in select patients with minimal nephrolithiasis. Long-term randomized placebo-controlled trials are needed to better define the precise role of lupeol-based PT vs. citrate therapy in minimal nephrolithiasis.

Calcium: An Essential Mineral

This review of calcium discusses briefly the role of the parathyroid glands, the gastrointestinal system, and the renal system in maintaining calcium homeostasis that is required for normal bone health, nerve and muscle function, and blood coagulation in the human body. The new recommendations for calcium intake by the United States Institute of Medicine are discussed. The concerns by the Institute of Medicine regarding adverse effects from excess calcium intake, especially hypercalcemia, nephrolithiasis (kidney stones), milk alkali syndrome, prostate cancer, and coronary heart disease, are reviewed.

Cooperation of phosphates and carboxylates controls calcium oxalate crystallization in ultrafiltered urine

Osteopontin (OPN) is one of a group of proteins found in urine that are believed to limit the formation of kidney stones. In the present study, we investigate the roles of phosphate and carboxylate groups in the OPN-mediated modulation of calcium oxalate (CaOx), the principal mineral phase found in kidney stones. To this end, crystallization was induced by addition of CaOx solution to ultrafiltered human urine containing either human kidney OPN (kOPN; 7 consecutive carboxylates, 8 phosphates) or synthesized peptides corresponding to residues 65-80 (pSHDHMDDDDDDDDDGD; pOPAR) or 220-235 (pSHEpSTEQSDAIDpSAEK; P3) of rat bone OPN. Sequence 65-80 was also synthesized without the phosphate group (OPAR). Effects on calcium oxalate monohydrate (COM) and dihydrate (COD) formation were studied by scanning electron microscopy. We found that controls form large, partly intergrown COM platelets; COD was never observed. Adding any of the polyelectrolytes was sufficient to prevent intergrowth of COM platelets entirely, inhibiting formation of these platelets strongly, and inducing formation of the COD phase. Strongest effects on COM formation were found for pOPAR and OPAR followed by kOPN and then P3, showing that acidity and hydrophilicity are crucial in polyelectrolyte-affected COM crystallization. At higher concentrations, OPAR also inhibited COD formation, while P3, kOPN and, in particular, pOPAR promoted COD, a difference explainable by the variations of carboxylate and phosphate groups present in the molecules. Thus, we conclude that carboxylate groups play a primary role in inhibiting COM formation, but phosphate and carboxylate groups are both important in initiating and promoting COD formation.

Prevention of renal crystal deposition by an extract of Ammi visnaga L. and its constituents khellin and visnagin in hyperoxaluric rats

In Egypt, teas prepared from the fruits of Ammi visnaga L. (syn. "Khella") are traditionally used by patients with urolithiasis. The aim of this study was to evaluate whether oral administration of an aqueous extract prepared from the fruits of A. visnaga as well as two major constituents khellin and visnagin could prevent crystal deposition in stone-forming rats. Hyperoxaluria was induced in male Sprague-Dawley rats by giving 0.75% ethylene glycol and 1% ammonium chloride via the drinking water. The Khella extract (KE; 125, 250 or 500 mg/kg) was orally administered for 14 days. The histopathological examination of the kidneys revealed that KE significantly reduced the incidence of calcium oxalate (CaOx) crystal deposition. In addition, KE significantly increased urinary excretion of citrate along with a decrease of oxalate excretion. Comparable to the extract, khellin and visnagin significantly reduced the incidence of CaOx deposition in the kidneys. However, both compounds did not affect urinary citrate or oxalate excretion indicating a mechanism of action that differs from that of the extract. For KE, a reasonably good correlation was observed between the incidence of crystal deposition, the increase in citrate excretion and urine pH suggesting a mechanisms that may interfere with citrate reabsorption. In conclusion, our data suggest that KE and its compounds, khellin and visnagin, may be beneficial in the management of kidney stone disease caused by hyperoxaluria but that it is likely that different mechanism of action are involved in mediating these effects.

The adult vitamin and mineral supplement maze

OBJECTIVE

The content and daily cost of 14 popular multi-vitamin/ multi-mineral (MVMM) supplements promoted for adults 50 years of age or older in the United States were compared in order to provide pharmacists with objective information, enabling them to make more informed recommendations for these products.

DATA SOURCES

The labeled ingredients for MVMM products contained on Drug Topic's "Top 200" over-the-counter product list and for several other popular brands were compared with the Institute of Medicine's (IOM) recommendations for the Dietary Reference Intake (DRI) of micronutrients.

DATA SYNTHESIS

DRIs for micronutrients are generally the same for adults between ages 31 to 70. However, vitamin B6, vitamin D, and calcium have increased daily DRIs for adults 50 years of age or older, and the DRI for vitamin D for those 70 years of age and older is higher. All products reviewed met IOM's recommendations for vitamin B6 and vitamin D for individuals 70 years of age or older. No product contained the daily DRI for calcium, particularly products designed for men. The cost and number of tablets per daily dose for MVMM varies and may affect product selection.

CONCLUSIONS

The most significant difference among MVMM products is the calcium content. IOM's recommendations for calcium are the same for both genders 50 years of age or older, but products developed for men contain very low amounts of calcium compared with products for women. Individuals who have a low dietary intake of vitamin D and calcium should take additional supplements with a daily MVMM. Formulations change frequently, and pharmacists should read labeling before making any specific product recommendations.