Urinary Cobalt Research Articles

Quantifying cobalt in doping control urine samples--a pilot study.

Since first reports on the impact of metals such as manganese and cobalt on erythropoiesis were published in the late 1920s, cobaltous chloride became a viable though not widespread means for the treatment of anaemic conditions. Today, its use is de facto eliminated from clinical practice; however, its (mis)use in human as well as animal sport as an erythropoiesis-stimulating agent has been discussed frequently. In order to assess possible analytical options and to provide relevant information on the prevalence of cobalt use/misuse among athletes, urinary cobalt concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS) from four groups of subjects. The cohorts consisted of (1) a reference population with specimens of 100 non-elite athletes (not being part of the doping control system), (2) a total of 96 doping control samples from endurance sport athletes, (3) elimination study urine samples collected from six individuals having ingested cobaltous chloride (500 µg/day) through dietary supplements, and (4) samples from people supplementing vitamin B12 (cobalamin) at 500 µg/day, accounting for approximately 22 µg of cobalt. The obtained results demonstrated that urinary cobalt concentrations of the reference population as well as the group of elite athletes were within normal ranges (0.1-2.2 ng/mL). A modest but significant difference between these two groups was observed (Wilcoxon rank sum test, p < 0.01) with the athletes' samples presenting slightly higher urinary cobalt levels. The elimination study urine specimens yielded cobalt concentrations between 40 and 318 ng/mL during the first 6 h post-administration, and levels remained elevated (>22 ng/mL) up to 33 h. Oral supplementation of 500 µg of cobalamin did not result in urinary cobalt concentrations > 2 ng/mL. Based on these pilot study data it is concluded that measuring the urinary concentration of cobalt can provide information indicating the use of cobaltous chloride by athletes. Additional studies are however required to elucidate further factors potentially influencing urinary cobalt levels.

Increased urinary cobalt and whole blood concentrations of cadmium and lead in women with uterine leiomyomata: Findings from the ENDO Study.

Multiple trace elements have estrogen receptor activity, but the association of these elements with uterine leiomyoma has not been defined. A cohort of 473 women aged 18-44 undergoing surgery for benign gynecologic indications provided whole blood and urine specimens for trace element analysis, which was performed by inductively coupled plasma mass spectrometry. Twenty elements were analyzed in blood and 3 in urine. The surgeon documented whether fibroids were present. Geometric mean concentrations were compared between women with and without fibroids, and logistic regression models were generated to assess the impact of the concentration of each trace element on the odds of fibroids. In multivariate regressions, odds of a fibroid diagnosis were higher with increased whole blood cadmium (AOR 1.44, 95% CI 1.02, 2.04) and lead (AOR 1.31 95% CI 1.02, 1.69), and urine cobalt (AOR 1.31, 95% CI 1.02, 1.70). Urinary cadmium and lead were not related to fibroid diagnosis. Increased exposure to trace elements may contribute to fibroid growth, and fibroids may serve as a reservoir for these elements. Differences between urinary and whole blood findings merit further investigation, as urinary cadmium has been considered a superior marker of exposure.

Higher urinary heavy metal, arsenic, and phthalate concentrations in people with high blood pressure: US NHANES, 2009–2010

Background: A link between environmental chemicals and human health has emerged but not complete in risk factors. This work aimed to study the relationships of different sets of urinary environmental chemical concentrations and risk of high blood pressure (BP) in a national, population-based study. Methods: Data was retrieved from United States National Health and Nutrition Examination Surveys, 2009–2010, including demographics, BP readings and urinary environmental chemical concentrations. Analyses included t-test and survey-weighted logistic regression models. Results: Urinary mercury concentrations were not associated with high BP (OR = 1.19, 95% CI 0.97–1.48, p = 0.095). Urinary cobalt (OR = 1.35, 95% CI 1.01–1.81, p = 0.044), lead (OR = 1.77, 95% CI 1.31–2.38, p = 0.001), antimony (OR = 1.37, 95% CI 1.09–1.72, p = 0.010) and tungsten (OR = 1.52, 95% CI 1.27–1.81, p < 0.001) concentrations were observed to increase the risk of high BP. There are no clear associations between environmental parabens and high BP. The effect of environmental bisphenol A (OR = 1.14, 95% CI 1.00–1.30, p = 0.051) disappeared after additionally adjusting for subsample weighting (OR = 1.12, 95% CI 0.93–1.35, p = 0.225). People with higher urinary mono-2-ethyl-5-carboxypentyl phthalate (OR = 1.26, 95% CI 1.00–1.58, p = 0.051), mono-n-butyl phthalate (OR = 1.19, 95% CI 1.01–1.41, p = 0.042) and mono-n-methyl phthalate metabolites (OR = 1.16, 95% CI 1.03–1.32, p = 0.021) tended to have high BP. Moreover, urinary o-phenyl phenol concentrations (OR = 1.49, 95% CI 1.25–1.77, p < 0.001) and dimethylarsonic acid concentrations (OR = 1.35, 95% CI 1.06–1.73, p = 0.019) were also seen to be associated with high BP. Conclusions: Urinary environmental chemical concentrations were associated with risk of high BP, although the causal effect cannot be established. Elimination of environmental chemicals in humans would need to be continued.

Predictivity and Fate of Metal Ion Release From Metal-On-Metal Total Hip Prostheses

Blood metal ion levels in 72 patients with large head metal-on-metal hip arthroplasty were studied to determine the correlation between the values measured in whole blood and urine. Urinary cobalt and chromium levels of 30μg and 21μg, respectively, adjusted to creatinine were found to correspond to the 7μg/l cut-off value that has been accepted in whole blood. Cobalt and chromium levels in whole blood and urine both significantly correlated with increased acetabular component inclination angle over 50 degrees and pain scores. There was no correlation with socket anteversion angle or femoral head diameter. The data support the use of urinary measurement of metal ions adjusted to creatinine to monitor patients with large head metal-on-metal total hip arthroplasty.

The Effect Of Different Bearing Surfaces On Metal Ion Levels In Urine Following 28 Mm Metal-On-Metal And 28 Mm Metal-On-Polyethylene Total Hip Arthroplasty

Recent advancements in manufacturing technology have enabled more precise tolerances and surface finishes using metal-on-metal bearing surfaces in total hip arthroplasty. The aim of this study was to compare the level of metal ions in urine after implantation of a 28-mm metal-on-metal bearing manufactured from high-carbon wrought alloy and a 28-mm metal-on-polyethylene bearing. A total of 92 total hip arthroplasty patients were prospectively randomized into two groups: those receiving metal-on-metal bearings and those receiving metal-on-polyethylene bearings. Chromium, cobalt, and molybdenum ion levels in urine were measured preoperatively and at 1 year and 2 years postoperatively. In the metal-on-polyethylene group, there was a slight increase in mean chromium and cobalt concentrations at 2-year follow-up compared to the preoperative level (p = 0.02 for both chromium and cobalt). In the metal-on-metal group, there was a 15-fold increase in chromium and a 26-fold increase in cobalt at 2-year follow-up compared to the preoperative level (p < 0.001 for both chromium and cobalt). However, the quantity of chromium and cobalt in urine from the metal-on-metal group was not higher at 2-year follow-up than at 1-year follow-up (p = 0.5 and p = 0.6, respectively). The 28-mm metal-on-metal bearings yield chromium and cobalt concentrations in urine that can be higher than those recommended for occupational exposure. However, our results also indicate that a steady state in wear and ion production using metal-on-metal total hip arthroplasty can occur.

Occupational exposure to cobalt is not associated with incipient signs of dilated cardiomyopathy in a Belgian refinery

BackgroundExcessive absorption of cobalt has been associated with cases of dilated cardiomyopathy in the past, but it is unclear whether occupationally exposed populations are at risk.ObjectiveTo assess the possible relationship...

Breast Milk Metal Ion Levels in a Young and Active Patient With a Metal-On-Metal Hip Prosthesis

Metal-on-metal resurfacing arthroplasty of the hip has been used increasingly over the last 10 years in younger active patients. The dissolution of the metal wear particles results in measurable increases in cobalt and chromium ions in the serum and urine of patients with a metal-on-metal bearing. We measured the cobalt, chromium, and molybdenum ion levels in urine; serum; and breast milk in a young and active patient with a metal-on-metal hip prosthesis after a pathologic fracture of the femoral neck. Metal-on-metal hip prosthesis leads to increasing levels of molybdenum in breast milk in the short-term follow-up. There are no increasing levels of chromium and cobalt ions in breast milk. Besides the already known elevated concentrations in serum of chromium and cobalt after implantation of a metal-on-metal hip prosthesis, we found no increasing levels of chromium and cobalt in urine.

An outbreak of occupational asthma due to chromium and cobalt

Five metal turners employed by an aerospace manufacturer presented to the Birmingham Chest Clinic occupational lung disease unit. Four cases of occupational asthma (OA) due to chromium salt (3) and cobalt (1) were diagnosed by serial peak-expiratory flow measurements and specific inhalation challenge testing. To measure the extent of the outbreak and to provide epidemiological data to ascertain the aetiology. Participants answered a detailed, self-administered questionnaire, designed to detect occupational lung disease. Urine chromium and cobalt excretion, spirometry and exhaled nitric oxide measurements were taken. Those with possible, probable or definite non-OA or OA, after questionnaire, were invited to undertake two-hourly peak flow measurements and received specialist follow-up. A total of 62 workers (95% of workforce) participated. Sixty-one per cent of employees were working in higher metalworking fluid (MWF) exposure areas. Ninety per cent of workers had urinary chromium excretion indicating occupational exposure. Sixty-six per cent of workers reported active respiratory symptoms, although there were no significant differences between exposure groups. Two further workers with probable OA were identified and had significantly higher urinary chromium and cobalt concentration than asymptomatic controls. Eighteen cases of occupational rhinitis (OR) were identified, with significantly raised urinary chromium concentration compared with asymptomatic controls. Chromium salt and cobalt can be responsible for OA and OR in workers exposed to MWF aerosols. Onset of symptoms in those with positive specific challenges followed change in MWF brand. Workers with OA had increased urinary concentrations of chromium and cobalt, and those with OR had increased urinary concentrations of chromium.

Cobalt and Chromium Levels in Blood and Urine Following Hip Resurfacing Arthroplasty with the Conserve Plus Implant

Cobalt and Chromium Levels in Blood and Urine Following Hip Resurfacing Arthroplasty with the Conserve Plus Implant

Cobalt and Chromium Levels in Blood and Urine Following Hip Resurfacing Arthroplasty with the Conserve Plus Implant

The purpose of the present study was to determine cobalt and chromium ion levels in the blood and urine of patients in whom a modern-generation metal-on-metal hip resurfacing device had been implanted. A total of ninety-seven patients with a Conserve Plus metal-on-metal hip resurfacing implant were followed prospectively for two years. Cobalt and chromium levels in erythrocytes, serum, and urine were measured preoperatively as well as three, six, twelve, and twenty-four months postoperatively. The median serum cobalt and chromium ion levels were 1.04 μg/L (range, 0.31 to 7.42 μg/L) and 2.00 μg/L (range, 0.28 to 10.49 μg/L), respectively, at one year after surgery and 1.08 μg/L (range, 0.44 to 7.13 μg/L) and 1.64 μg/L (range, 0.47 to 10.95 μg/L), respectively, at two years after surgery. The corresponding mean levels (and standard deviations) of serum cobalt and chromium were 1.68 ± 1.66 μg/L and 2.70 ± 2.22 μg/L, respectively, at one year after surgery and 1.79 ± 1.66 μg/L and 2.70 ± 2.37 μg/L, respectively, at two years after surgery. These levels compare favorably with other published ion results for metal-on-metal hip resurfacing and replacement implants. No pseudotumors or other adverse soft-tissue reactions were encountered in our study population. Further research is needed to determine the clinical importance of increased cobalt and chromium ion levels in serum and urine following metal-on-metal hip resurfacing.

Heavy Metals and Cardiovascular Disease: Results from the National Health and Nutrition Examination Survey (NHANES) 1999-2006

We assessed the role of lead and cadmium as partial mediators between smoking and composite cardiovascular and cerebrovascular disease (CCVD). We also studied the association between urinary heavy metals and CCVD. Pooled data from NHANES 1999-2006 were examined. Cardiovascular and cerebrovascular disease was determined using a standardized questionnaire asking about history of stroke, angina, heart attack, coronary artery disease, and congestive heart failure. Increasing serum cadmium levels were associated with increasing prevalence of CCVD (P-trend: .03). Adjusted odds-ratio (OR) for active smokers versus never smokers was 2.09 (1.67-2.63). Adjustment for lead did not affect the OR but adjustment for cadmium significantly attenuated the OR (1.54 [1.17-2.03]). Significant association was observed between CCVD and urinary antimony, cadmium, cobalt, and tungsten. High levels of serum cadmium (>0.61 µg/L) were associated with CCVD. The relationship between smoking and CCVD was partially mediated through cadmium. Urinary antimony, cadmium, cobalt, and tungsten may be associated with CCVD.

Absence of adverse effect on thyroid function and red blood cells in a population of workers exposed to cobalt compounds

Context Hypothyroidism has been observed in the fifties and sixties as an undesirable side-effect of cobalt therapy used for its erythropoietic properties in the treatment of anemia. Objective This study aims at evaluating the possible impact of both cumulative (long-term) and recent occupational exposure to cobalt on thyroid function and red blood cells. Methods and setting A cross-sectional survey was conducted from February 2008 to August 2009 in a population of 249 male workers from a cobalt production department in the North of Belgium. The possible effect of cobalt exposure on thyroid and red blood cells was investigated through multiple regression analyses. Results Blood cobalt ranged from undetectable to 3.20 μg/100 ml (median 0.10); urinary cobalt from 0.30 to 204.30 μg/g creat (median 3.90) and long-term exposure to cobalt ranged from 0.15 to 6990.46 μg/g creat·years (median 106.09). No effect of cobalt exposure on thyroid or red blood cell parameters was observed at these levels of exposure. Conclusion The results support the absence of effects on the thyroid and red blood cells when occupational exposure to cobalt is kept below the recommended biological limit of occupational exposure (15 μg Co/g creat in urine).

An autism cohort study of cobalt levels following vitamin B12 injections

The effects of methylcobalamin (vitamin B12) injection (75 µg kg−1) on cobalt levels in autism spectrum disorders (ASDs) and potential toxic effects of cobalt on human neurons were evaluated. A cohort of ASDs (n = 72) presenting to the Genetic Centers of America were evaluated for the frequency of methylcobalamin injections and cobalt levels using Laboratory Corporation of America (LabCorp) testing. Potential toxic effects of cobalt (cobalt(II) nitrate hexahydrate) to human neurons grown in vitro were evaluated. Methylcobalamin injections significantly increased the mean levels of plasma cobalt (6.83-fold) and urinary cobalt (51-fold) in comparison to unexposed subjects, and significant positive correlations were found between the frequency of methylcobalamin injections and the levels of plasma and urinary cobalt (injections every second day induced cobalt levels in excess of the LabCorp cobalt occupational maximum exposure limits). The LC50 in human neurons following 24 h incubation with cobalt is 559 µM. Research must be conducted to determine optimal therapeutic methylcobalamin doses.

Renal Clearance of Cobalt in Relation to the Use of Metal-on-Metal Bearings in Hip Arthroplasty

A concern regarding the use of metal-on-metal bearings in hip arthroplasty has been that the high levels of metal ions that are released overwhelm the renal threshold for metal excretion, leading to systemic buildup of metals. The purpose of this investigation was to determine if the physiological renal capacity for cobalt clearance and cobalt concentrating efficiency is overwhelmed by the elevation in metal ion levels seen in patients with metal-on-metal-bearing hip devices. Concurrent specimens of urine and plasma were obtained from a group of 461 patients (346 men and 115 women) at various intervals after either a unilateral (296) or a bilateral (130) metal-on-metal hip arthroplasty or preoperatively (thirty-five patients; the control specimens). Metal ion analyses were performed with high-resolution inductively coupled mass spectrometry. Renal efficiency was measured as the ratio of urine cobalt concentration to plasma cobalt concentration. Cobalt clearance was calculated by dividing the urine cobalt output in twenty-four hours by the plasma cobalt concentration. Dividing the quotient by 1440 adjusts it to clearance per minute. The median renal efficiency was found to be 0.9 in the analysis of the preoperative specimens, indicating that there was renal conservation of cobalt. In patients with metal-on-metal bearings, the median renal efficiency was 3.2, indicating that, as a result of cobalt excretion, the cobalt concentration in urine was threefold higher than the concentration in plasma. Linear regression analysis showed that renal efficiency progressively increased at a rate of 9% for every microg/24 hr increase in cobalt release. Cobalt clearance showed a similar trend, increasing from 1.3 mL/min in the preoperative group to 3.7 mL/min in the follow-up group. In the follow-up group, renal cobalt clearance progressively increased from 1.9 to 7.1 mL/min with increasing daily cobalt output, which indicates that with increasing in vivo metal ion release there was a progressive increase in the rate at which the kidneys cleared the plasma of cobalt. In subjects with no prosthetic device, the kidneys tend to conserve cobalt in the body. We found that, in patients with a metal-on-metal hip prosthesis, there is a progressive increase in cobalt clearance with increasing in vivo wear at the levels of cobalt release expected in patients with an array of metal-on-metal-bearing total joint arthroplasties. We found no threshold beyond which renal capacity to excrete these ions is overwhelmed.

Occupational Exposure to Cobalt: A Population Toxicokinetic Modeling Approach Validated by Field Results Challenges the Biological Exposure Index for Urinary Cobalt

This study modeled the urinary toxicokinetics of cobalt exposure based on 507 urine samples from 16 workers, followed up for 1 week, and 108 related atmospheric cobalt measurements to determine an optimal urinary cobalt sampling strategy at work and a corresponding urinary exposure threshold (UET). These data have been used to calibrate a population toxicokinetic model, taking into account both the measurement uncertainty and intra- and interindividual variability. Using the calibrated model, urinary sampling sensitivity and specificity performance in detecting exposure above the 20 μg/m3 threshold limit value – time-weighted average (TLV-TWA) has been applied to identify an optimal urine sampling time. The UET value is obtained by minimizing misclassification rates in workplace exposures below or above the TLV. Total atmospheric cobalt concentrations are in the 5–144 μg/m3 range, and total urinary cobalt concentrations are 0.5–88 μg/g creatinine. A two-compartment toxicokinetic model best described urinary elimination. Terminal elimination half-time from the central compartment is 10.0 hr (95% confidence interval [8.3–12.3]). The optimal urinary sampling time has been identified as 3 hr before the end of shift at the end of workweek. If we assume that misclassification errors are of equal cost, the UET associated with the TLV of 20 μg/m3 is 5 μg/L, which is lower than the ACGIH-recommended biological exposure index of 15 μg/L. [Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Occupational and Environmental Hygiene for the following free supplemental resource: an appendix with discussion of the toxicokinetic model, priors, model checking, cross validation, and comparison of ROC curves for various urinary sampling strategy.]

Octadecyl Bonded Silica Membrane Disk Modified with Cyanex302 for Preconcentration and Determination of Traces of Cobalt in Urine by Flame Atomic Absorption Spectrometry

Octadecyl bonded silica membrane disk was impregnated with Cyanex302 for flame atomic absorption spectrometric determination of traces of cobalt(II) in urine. The solid phase extraction method developed using the modified disk was systematically investigated for sorption-desorption of cobalt(II). Cobalt(II) was quantitatively sorbed on the disk at pH 6.0 and eluted using 15 cm3 of 1 × 10−3 M HCl. The lower limit of detection for cobalt(II) was 1.5 µg dm−3 and the preconcentration factor 133 with a precision in terms of relative standard deviation (% R. S. D.) 0.6. The reusability of the modified disk was ≥35 cycles.

Biological monitoring of tungsten (and cobalt) in workers of a hard metal alloy industry

To evaluate a combined biomonitoring approach based on both cobalt and tungsten determination in workers of the hard metal alloy sector. We enrolled 55 workers from a factory producing cutting tools for carpentry. Combined workroom air and biological monitoring of both cobalt and tungsten relied on inductively coupled plasma mass spectrometry determinations. Metals were determined on plasma, blood and urine samples. Urine samples from 34 unexposed subjects were also analyzed. Tungsten was determined in every collected sample. Workers showed significantly higher urinary tungsten levels than controls (pre-shift values of 4.12 vs. 0.06 microg/l on average; P < 0.0005). Both airborne and biological levels of tungsten prevailed among workers involved in wet-grinding activities. The element was excreted at higher urinary levels than cobalt and showed lower circulating (blood, plasma) concentrations. Exposure-dose relationships were apparent for tungsten biomarkers. Obtained results may contribute to the development of biomarkers of exposure to tungsten. The association of such biomarkers to traditional determinations of cobalt in blood and/or urine may substantially improve the exposure assessment of workers employed in cemented carbide industries.

Literature Review

Cobalt is a relatively rare element of the Earth’s crust, essential to mammals in the form of cobalamin (vitamin B12). In humans, dietary intake of cobalt varies between 5 and 50 μg/day and most of it is inorganic with vitamin B12 representing only a small fraction. The oral bioavailability of inorganic cobalt compounds is a function of their water solubility and varies from 5 to 45%. In occupational settings, workers are exposed to mainly inorganic cobalt compounds by inhalation of dust. The absorption rate of inhaled cobalt also varies with the species under consideration. Cobalt does not accumulate in the organism and is rapidly excreted, mainly in urine. The concentration of cobalt in urine or in blood can be used as a biomarker of recent exposure to soluble cobalt species. Cobalt(II) ions are genotoxic and several forms of cobalt are carcinogenic in experimental animals. Upon inhalation exposure, the respiratory system is the main target organ of cobalt in humans (asthma, fibrosing alveolitis, lung cancer), with a higher risk of fibrosing alveolitis (hard metal disease) and lung cancer in the hard metal industry, where workers are exposed to cobalt metal mixed with tungsten carbide particles. Other target organs include the hematopoietic system, the myocardium, the thyroid gland, and the nervous system. Endogenous exposure to cobalt, sometimes associated with local and/or systemic toxicity, can occur in patients with cobalt alloy implants, especially metal-on-metal hip prostheses. The reproductive toxicity of cobalt compounds is not well documented.

Application of electrospray ionization tandem mass spectrometry for the rapid and sensitive determination of cobalt in urine

Recently, cobalt (Co) is reported to be taken as a supplement by athletes for improving anaerobic performance. For the diagnosis of abuse, the limit of detection (LOD) of Co in the analysis should be lower than the concentrations of Co in plasma and urine of normal persons. A simple, rapid and sensitive method has been developed for the determination of Co in urine. Co was complexed with diethyldithiocarbamate (DDC) and extracted with isoamyl alcohol in the presence of citric acid. The detection of Co was achieved by injecting a 1-μL aliquot of isoamyl alcohol containing Co–DDC complex directly into an electrospray ionization tandem mass spectrometric (ESI-MS–MS) instrument without chromatographic separation. The quantification was performed using selected reaction monitoring at m/ z 291 of the product ion Co(C 4H 10NCS) 2 + which was produced by collision-induced dissociation from the precursor ion Co(DDC) 2 + at m/ z 355. ESI-MS–MS data were obtained in less than 10 min with an LOD of 0.05 μg L −1 and a linear calibration range of 0.1–100 μg L −1 using 10 μL of urine. The procedure was validated with certified reference materials (SRM 2670a and SRM 1643e). This method is suitable for the analysis of Co in the laboratories already equipped with an ESI-MS–MS instrument.

Determination of serum levels of cobalt and chromium in 17 patients undergoing metal-on-metal THR

To assess cobalt and chromium concentrations in serum and urine in 17 patients that underwent total hip replacement (THR) with a metal-on-metal bearing and to determine their correlation with radiographical findings. Cobalt and chromium concentrations were measured in 17 patients by means of atomic absorption spectrophotometry before implantation of a metal-on-metal THR, between the first and second year post-op and between the third and fourth year post-op. Cobalt and chromium concentrations in urine were also determined at the end of follow-up. The post-op radiological study was compared with that carried out at the end of follow-up. Mean patient age was 57 ± 6 years and mean follow-up was 31 ± 9 months. Mean cobalt concentration did not rise during the first and second year post-op with respect to the mean preop concentration, but it did increase between the third and fourth year. Mean chromium concentration rose between the first and second year and they went on to drop slightly between the third and fourth year post-op. No relationship was found between the appearance of radiolucent lines or a varus or valgus position of the stem and the cobalt and chromium levels in serum and urine. Eighty-five percent of cups with an inclination > 56° showed cobalt and chromium concentrations in serum in excess of the mean pre-op value. The increase in mean serum cobalt and chromium concentrations detected in our study was lower than that shown by other authors. This increase occurred mainly between the first and second year post-op. The series under study shows that the more vertically the cup is placed the higher the cobalt and chromium levels present. Valorar los niveles de cobalto y cromo en suero y orina en 17 pacientes tras el implante de una prótesis total de cadera (PTC) con par de fricción metal-metal y su correlación con los hallazgos radiológicos. Se determinaron en 17 pacientes, mediante espectrofotometría de absorción atómica, las concentraciones de cobalto y cromo en suero antes de la implantación de una PTC metal-metal, entre el primer y segundo año, y entre el tercer y cuarto año tras la intervención, y las concentraciones de cobalto y cromo en orina al final del seguimiento. Se comparó el estudio radiológico postoperatorio con el realizado al final de seguimiento. La edad media de los pacientes fue de 57 ± 6 años, y el tiempo medio de seguimiento de 31 ± 9 meses. La concentración media de cobalto no se elevó durante el primer y segundo año tras la intervención respecto a la concentración media preoperatoria, y sí lo hizo entre el tercer y cuarto año. La concentración media de cromo se elevó durante el primer y segundo año, para descender ligeramente entre el tercer y cuarto año tras la intervención. No se evidenció ninguna relación entre la aparición de líneas de radiolucencia o la colocación del vástago en varo o valgo con los niveles de cobalto y cromo en suero y orina. El 85% de los cotilos con una inclinación superior a 56° presentaron concentraciones de cobalto y cromo en suero por encima de la media preoperatoria. El incremento de las concentraciones medias de cobalto y cromo en suero detectado en nuestra serie fue menor respecto a otros estudios. Este incremento se produjo principalmente entre el primer y segundo año tras la intervención. En la serie estudiada se aprecia un incremento de los niveles de cobalto y cromo en relación con la verticalización del cotilo.