Clomiphene for the Treatment of Male Infertility: A Case Report of Mood Change and a Literature Overview.

BACKGROUND: Clomiphene is normally used in women with ovulatory dysfunction. In men, it is used off label in some cases of infertility. Psychological adverse effects are reported in women but very few in men. CASE: A 34-year-old man treated with clomiphene for oligoteratospermia presented anxiety, decreased appetite, and mood change making him unable to function properly at work, five days after initiation of therapy. Symptoms required reduction followed by discontinuation of treatment four days later because of absence of improvement. Following cessation, the patient noted a gradual then a complete resolution approximately one week later. The patient did not have any psychiatric or other medical condition neither drug nor substance abuse that could explain this clinical presentation. The Naranjo's score was used to prove the clomiphene's imputability. CONCLUSION: Health care providers should advise patients of the risk of psychological adverse effects when initiating treatment with clomiphene and should provide a close monitoring of mood change, especially during the initial weeks.

Minimally invasive vs open pyeloplasty in children: the differential effect of procedure volume on operative outcomes.

OBJECTIVE: To assess the differential effect of volume-outcome dynamics on the outcomes of open pyeloplasty (OP) and minimally invasive pyeloplasty (MIP) in the management of pediatric ureteropelvic junction obstruction in the setting of increasing utilization of MIP. METHODS: Within the Nationwide Inpatient Sample, a weighted estimate of 6006 pediatric patients (≤18 years; 2008-2010) with ureteropelvic junction obstruction underwent either OP or MIP. National trends in utilization and comparative effectiveness outcomes were examined in terms of intraoperative and postoperative complications, prolonged length of stay, and excessive hospital charges. Hospitals were stratified into volume quartiles. Specifically, the volume-outcome dynamics of the highest and lowest volume quartiles of both the approaches were examined with binary logistic regression models. RESULTS: MIP accounted for 17.2% of cases during the study years. In individual multivariate models, high-volume OP patients had a significantly lower risk of developing postoperative complications, genitourinary complications, and excessive hospital charges compared with high-volume MIP, low-volume OP, and low-volume MIP patients. Regardless of hospital volume, MIP patients experienced shorter hospital stays. CONCLUSION: Although there has been a substantial increase in the utilization of MIP, high-volume hospitals performing OP have the best perioperative outcomes in terms of postoperative complications, genitourinary complications, and overall hospital charges. However, high-volume hospitals performing MIP have better outcomes compared with low-volume hospitals performing OP. Shorter hospital stay is the one mitigating factor of MIP.

Updated assessment of neobladder utilization and morbidity according to urinary diversion after radical cystectomy: A contemporary US-population-based cohort.

BACKGROUND: In this paper, we examine contemporary utilization rates and determinants of neobladder (NB) after radical cystectomy (RC) relative to ileal conduit (IC), as well as provide an updated assessment of postoperative morbidity and mortality between NB and IC. METHODS: Relying on the Nationwide Inpatient Sample (NIS), we abstracted patients who underwent RC between 2000 and 2010. Subsequently, NB and IC recipients were identified. Use of NB was assessed after accounting for case-mix. Propensity-based matched analyses were used to account for treatment selection biases. Generalized linear regression analyses focused on intra- and postoperative complications, prolonged length of stay, blood transfusions and in-hospital mortality. RESULTS: The utilization rate of NB was 6.9% in 2000 and 9.1% in 2010 (p < 0.001). Younger, healthier, privately-insured and wealthier male individuals were more likely to receive a NB. High-volume hospitals were more likely to offer NB. In the post-propensity matched cohort, urinary diversion type failed to be significantly associated with the examined endpoints, except for intra- and postoperative complications (IC vs. NB odds ratio [OR]: 1.15, p = 0.04). INTERPRETATION: Despite comparable morbidity and mortality odds between NB and IC, as of the most contemporary year of the study (2010), IC remains the preferred urinary diversion type. Several sociodemographic factors were associated with NB.

Incidence of priapism in emergency departments in the United States.

PURPOSE: Priapism is a complex medical emergency that often requires prompt management. In this study, we examine the incidence of this condition in a United States population based setting, and assess patient and emergency department attributes associated with an increased likelihood of hospitalization. MATERIALS AND METHODS: Emergency department visits with a primary diagnosis of priapism between 2006 and 2009 were abstracted from the Nationwide Emergency Department Sample. Univariable and multivariable analyses were performed of patient and hospital characteristics of those admitted with priapism. RESULTS: Between 2006 and 2009 a weighted estimate of 32,462 visits to the emergency department for priapism was recorded in the United States, which represents a national incidence of 5.34 per 100,000 male subjects per year. The incidence of emergency department visits increased by 31.4% during the summer compared to the winter months. Overall 4,320 visits (13.3%) resulted in hospitalization/admission for further management. On multivariable analyses independent predictors of admission included Charlson comorbidity index score 3 or greater (OR 5.67, p <0.001), insurance status (Medicaid vs private OR 1.60, p = 0.001), hospital location (rural vs urban nonteaching OR 0.32, p <0.001), median ZIP code income (very high OR 0.65, p = 0.005), emergency department volume (very high vs very low OR 1.61, p = 0.004), sickle cell disease (OR 2.22, p <0.001) and drug abuse (OR 5.47, p <0.001). CONCLUSIONS: Emergency department visits for priapism are relatively uncommon and occur more frequently during the summer months. The majority of patients are treated and released expediently. Predictors of hospital admission included comorbidity profile, insurance, hospital location and emergency department volume.

Effect of needle size on cancer detection, pain, bleeding and infection in TRUS-guided prostate biopsies: A prospective trial.

INTRODUCTION: Transrectal ultrasound (TRUS)-guided prostate biopsies using 18G calibre needles are widely used; most often 12-core tissue samples of the peripheral zone are obtained. Although the diagnostic yield of prostate biopsies is fair, there is still a potential for false negative results, which necessitates repeat biopsies. In an effort to improve the accuracy of prostate biopsies, different sampling schemes have been developed. One strategy has been to increase the number of core biopsies performed on each patient. Another strategy has been to improve the reliability of prostate biopsies using larger calibre needles, thereby increasing the amount of tissue obtained for each core biopsy. METHODS: After approval by our institutional review board, we prospectively compared two biopsy needle sizes (18G vs. 16G) in relation to prostate cancer diagnosis, pain, bleeding and infection rates on 105 patients. Each patient underwent 6 TRUS-guided prostate biopsies with the standard 18G needle and 6 other biopsies with the experimental 16G needle. To evaluate possible complications related to the use of a larger 16G needle in the experimental group, we compared pain, bleeding and infection rates with a control group of 100 patients who underwent 12 biopsies with a single 18G needle (18G group). Pain, bleeding assessment and infection events were evaluated using patient questionnaires and telephone interviews. RESULTS: TRUS-guided prostate biopsies using 16G calibre needles did not increase cancer detection or non-malignant pathology rate, including prostatic intraepithelial neoplasia (PIN) and atypical small acinar proliferatio (ASAP). Pain, bleeding and infectious complications were similar in both groups. Infection was defined as temperature above 38°C occurring within 48 hours after the procedure. We identified 4 patients with post-biopsy fever in the experimental (16/18G) group and 4 other patients in the (18G) control group. The post-biopsy infection rate is higher than reported just a few years ago and indicates that quinolone resistant Escherichia coli seems to be more prevalent in our urban setting than previously suspected. Limitations to our study include small group numbers. CONCLUSION: Larger 16G needles appear to be safe for TRUS-guided prostate biopsies. Further study in a larger, multi-institutional, prospective, randomized manner with 16G needles is warranted to assess the theoretical benefit of larger core biopsies in prostate cancer detection.

Marital status: a gender-independent risk factor for poorer survival after radical cystectomy.

UNLABELLED: Study Type - Prognosis (cohort) Level of Evidence 2a. What's known on the subject? and What does the study add? Married individuals have lower morbidity and mortality rates for all major causes of death. Cancer-specific survival is better in married patients with testis cancer, prostate cancer, breast cancer, cervical cancer, as well as head and neck cancers. We have found the effect of marital status on outcomes after radical cystectomy to be variable, depending on gender and the outcome addressed. Being married is predictive of lower all-cause mortality for both men and women relative to their separated, divorced or widowed (SDW) or never-married counterparts. It is also predictive of lower bladder-cancer-specific mortality relative to SDW individuals. Marriage also exerts a protective effect on men regarding non-organ-confined disease, with those never having married having significantly higher rates. OBJECTIVES: • To examine the effect of marital status (MS) on the rate of non-organ-confined disease (NOCD) at radical cystectomy (RC) • To assess the effect of MS on the rate of bladder-cancer-specific mortality (BCSM) and all-cause mortality (ACM) after RC for urothelial carcinoma of the urinary bladder (UCUB). MATERIALS AND METHODS: • A total of 14 859 patients, who underwent RC for UCUB, were captured within the Surveillance, Epidemiology, and End Results database, between 1988 and 2006. • Logistic regression analysis was used to assess the rate of NOCD (T(3-4) /N(I-3) /M(0) ) at RC and Cox regression analyses were used to assess BCSM and ACM. • Analyses were stratified according to gender; covariates included socio-economic status, tumour stage, age, race, tumour grade and year of surgery. RESULTS: • Never-married males had a higher rate of NOCD at RC (odds ratio = 1.22, P= 0.004), an effect not found in never-married females. • Separated, divorced or widowed (SDW) males (hazard ratio [HR]= 1.18, P= 0.005) and females (HR = 1.16, P= 0.002) had higher rates of BCSM than their married counterparts. • SDW and never-married males had higher rates of ACM than their married counterparts (HR = 1.22, P < 0.001 and HR = 1.26, P < 0.001, respectively). • SDW and never-married females also had higher rates of ACM than married females (HR = 1.24, P < 0.001 and HR = 1.22, P= 0.01, respectively). CONCLUSIONS: • For both men and women, being SDW conveyed an increased risk of BCSM after RC. • SDW and never marrying had a deleterious effect on ACM. • Unfavourable stage at RC was also seen more commonly in never-married males.

Development and validation of a reference table for prediction of postoperative mortality rate in patients treated with radical cystectomy: a population-based study.

PURPOSE: The existing literature suggests that the postoperative mortality (POM) rate in radical cystectomy (RC) patients does not exceed 3%. We sought to develop and externally validate a reference table that quantifies POM after RC. METHODS: We identified 12,274 patients treated with RC, between 1998 and 2007, within the Nationwide Inpatient Sample database. A total of 6188 (50.4%) randomly selected patients was used as the development cohort. Logistic regression analysis for prediction of POM adjusted for: age, sex, race, Charlson comorbidity index (CCI), urinary diversion type, year of surgery, annual hospital caseload, location/teaching status of hospital, region and bed size of hospital. The reference table was developed by using stepwise variable removal to identify the most accurate and parsimonious model. The model was externally validated in 6086 (49.6%) patients. RESULTS: POM occurred in 2.4% of patients. POM proportion increased with increasing age (≤59: 0.6% vs. 60-69: 1.6% vs. 70-79: 3.1% vs. ≥80: 4.6%, P < 0.001), and higher CCI (CCI 0: 1.7% vs. CCI 1: 3.0% vs. CCI 2: 4.2% vs. CCI 3: 4.3% vs. CCI ≥ 4: 12.1%, P < 0.001). In multivariable analyses, only age and CCI remained as independent predictors of POM, after stepwise variable removal. The discrimination accuracy of the reference table in predicting POM was 70%. CONCLUSIONS: Age and CCI represent the foremost determinants of POM after RC. The developed reference table is capable of predicting POM after RC, in an individualized fashion. The accuracy of the model is good (70%), and it is highly generalizable.

Survival after radical cystectomy of non-bilharzial squamous cell carcinoma vs urothelial carcinoma: a competing-risks analysis.

OBJECTIVES: • To test the effect of histological subtype (NBSCC vs UC) on cancer-specific mortality (CSM), after adjusting for other-cause mortality (OCM). • In Western countries, non-bilharzial squamous cell carcinoma (NBSCC) is the second most common histological subtype in bladder cancer (BCa) after urothelial carcinoma (UC). PATIENTS AND METHODS: • We identified 12,311 patients who were treated with radical cystectomy (RC) between 1988 and 2006, within 17 Surveillance, Epidemiology and End Results (SEER) registries. • Univariable and multivariable competing-risks analyses tested the relationship between histological subtype and CSM, after accounting for OCM. • Covariates consisted of age, sex, year of surgery, race, pathological T and N stages, as well as tumour grade. RESULTS: • Histological subtype was NBSCC in 614 (5%) patients vs UC in 11,697 (95%) patients. • At RC, the rate of non-organ confined (NOC) BCa was higher in NBSCC patients than in their UC counterparts (71.7% vs 52.2%; P < 0.001). • After adjustment for OCM, The 5-year cumulative CSM rates were 25.0% vs 19.8% (P= 0.2) for patients with NBSCC vs UC organ confined (OC) BCa, respectively. The same rates were 46.3% vs 49.3% in patients with NOC BCa (P= 0.1). • In multivariable competing-risks analyses, histological subtype (NBSCC vs UC) failed to achieve independent predictor status of CSM in patients with OC (hazard ratio, 1.2; P= 0.06) or NOC BCa (hazard ratio, 1.1; P= 0.1). CONCLUSIONS: • At RC, the rate of NOC BCa is higher in NBSCC patients than in their UC counterparts. • Despite a more advanced stage at surgery, NBSCC histological subtype is not associated with a less favourable CSM than UC histological subtype, after accounting for OCM and the extent of the disease (OC vs NOC).

Stage-specific impact of pelvic lymph node dissection on survival in patients with non-metastatic bladder cancer treated with radical cystectomy.

OBJECTIVE: To examine the effect of stage-specific pelvic lymph node dissection (PLND) on cancer-specific (CSM) and overall mortality (OM) rates at radical cystectomy (RC) for bladder cancer. METHODS: Overall, 11,183 patients were treated with RC within the Surveillance, Epidemiology, and End Results database. Univariable and multivariable Cox regression analyses tested the effect of PLND on CSM and OM rates, after stratifying according to pathological tumour stage. RESULTS: Overall, PLND was omitted in 25% of patients, and in 50, 35, 27, 16 and 23% of patients with respectively pTa/is, pT1, pT2, pT3 and pT4 disease (P < 0.001). For the same stages, the 10-year CSM-free rates for patients undergoing PLND compared with those with no PLND were, respectively, 80 vs 71.9% (P = 0.02), 81.7 vs 70.0% (P < 0.001), 71.5 vs 56.1% (P = 0.001), 43.7 vs 38.8% (P = 0.006), and 35.1 vs 32.0% (P = 0.1). In multivariable analyses, PLND omission was associated with a higher CSM in patients with pTa/is, pT1 and pT2 disease (all P ≤ 0.01), but failed to achieve independent predictor status in patients with pT3 and pT4 disease (both P ≥ 0.05). Omitting PLND predisposed to a higher OM across all tumour stages (all P ≤ 0.03). CONCLUSIONS: Our results indicate that PLND was more frequently omitted in patients with organ-confined disease. The beneficial effect of PLND on cancer control outcomes was more evident in these patients than in those with pT3 or pT4 disease. PLND at RC should always be considered, regardless of tumour stage.

Head-to-head comparison of three commonly used preoperative tools for prediction of lymph node invasion at radical prostatectomy.

OBJECTIVE: A formal validation and head-to-head comparison of the National Comprehensive Cancer Network (NCCN) practice guideline lymph node invasion (LNI) nomogram, Partin tables, and D'Amico risk-classification was conducted for prediction of LNI at radical prostatectomy (RP). METHODS: We focused on 20,877 patients treated with RP and pelvic lymph node dissection (PLND) between 2004 and 2006 within the Surveillance, Epidemiology and End Results database. The discrimination of the 3 tools in predicting histologically confirmed LNI was quantified using the area under the curve (AUC). Calibration plots were used to graphically depict the performance characteristics of the examined tools. In addition, we relied on decision curve analyses to compare the 3 models directly in a head-to-head fashion. RESULTS: Overall, 2.5% of patients had LNI. The NCCN LNI nomogram (AUC 82%) outperformed the Partin tables (73%) and the D'Amico risk-classification (75%) for prediction of LNI. Calibration plots revealed that all 3 tools overestimated the risk of LNI. Partin tables showed the highest net-benefit for probability threshold range between 1% and 4%. Conversely, the NCCN LNI nomogram showed the highest net-benefit for the remaining threshold probabilities. CONCLUSION: The NCCN LNI nomogram had the highest discrimination accuracy. However, using the decision curve analysis, the Partin tables demonstrated the highest net benefit when a threshold probability of LNI is <4%. In contrast, the NCCN LNI nomogram had the highest net benefit when the threshold probability used to perform PLND is greater than 4%.

Hospital and surgical caseload are predictors of comprehensive surgical treatment for bladder cancer: a population based study.

PURPOSE: In patients with nonmetastatic muscle invasive bladder cancer, radical cystectomy and pelvic lymph node dissection represent a comprehensive surgical treatment. We tested the hypothesis that radical cystectomy performed at a high caseload hospital and/or by a high caseload surgeon is more likely to include pelvic lymph node dissection. MATERIALS AND METHODS: We identified 12,274 patients with bladder cancer treated with radical cystectomy between 1998 and 2007 within the Nationwide Inpatient Sample. Univariable and multivariable analyses tested the relationship between hospital and surgical caseload at radical cystectomy, and the pelvic lymph node dissection rate. Generalized estimating equation models were used to adjust for clustering among hospitals and surgeons. RESULTS: Overall 70% of patients received comprehensive surgical treatment defined as radical cystectomy and pelvic lymph node dissection. The pelvic lymph node dissection rate was 63% vs 67% vs 80% for low vs intermediate vs high annual hospital caseload tertiles, respectively (p<0.001). The pelvic lymph node dissection rate was 64% vs 68% vs 80% for low vs intermediate vs high annual surgical caseload tertiles, respectively (p<0.001). On multivariable analyses and after adjusting for clustering, annual hospital caseload and annual surgical caseload were independent predictors of the pelvic lymph node dissection rate. CONCLUSIONS: Our findings indicate that a potentially comprehensive surgical treatment, defined as radical cystectomy with pelvic lymph node dissection, is only offered to a subset of patients. Annual hospital caseload and annual surgical caseload represent important determinants of potentially comprehensive bladder cancer surgery. Efforts should be made to ensure that virtually all patients with bladder cancer receive comprehensive surgical treatment.

The importance of pelvic lymph node dissection in the elderly population: implications for interpreting the 2010 National Comprehensive Cancer Network practice guidelines for bladder cancer treatment.

PURPOSE: National Comprehensive Cancer Network practice guidelines indicate that pelvic lymph node dissection can be omitted at radical cystectomy in elderly patients. We examined the pelvic lymph node dissection rate in patients 80 years old or older and the impact of pelvic lymph node dissection on cancer specific and overall mortality in these patients. MATERIALS AND METHODS: We examined the records of 11,183 patients treated with radical cystectomy in 17 Surveillance, Epidemiology and End Results registries. We performed univariate and multivariate Cox regression analysis to test the effect of pelvic lymph node dissection on cancer specific and overall mortality. RESULTS: Overall pelvic lymph node dissection was omitted in 25% of patients, including 24.2% younger than 80 years and 30.8% 80 years old or older (p <0.001). The 5-year rate of freedom from cancer specific mortality for pelvic lymph node dissection vs no pelvic lymph node dissection was 62.5% vs 59.9% in patients younger than 80 years, and 50.0% vs 46.1% in those 80 years old or older (p = 0.01 and 0.005, respectively). The 5-year rate of freedom from overall mortality for the same categories was 48.8% vs 43.9% and 28.3% vs 24.7% (p <0.001 and 0.01, respectively). On multivariate analysis omitting pelvic lymph node dissection was associated with a 1.3-fold higher cancer specific rate at ages less than 80 and 80 years or greater (each p <0.001). Omitting pelvic lymph node dissection was also associated with a 1.3-fold higher overall mortality rate, including 1.3 at ages less than 80 years and 1.2-fold at ages 80 years or greater (each p ≤0.005). CONCLUSIONS: Results indicate that pelvic lymph node dissection was more often omitted in patients 80 years old or older than in those younger than 80 years. However, the protective effect of pelvic lymph node dissection on cancer specific and overall mortality was virtually the same in the 2 age categories. Thus, advanced age should not be a limiting factor for performing pelvic lymph node dissection at radical cystectomy.

Surgical caseload is an important determinant of continent urinary diversion rate at radical cystectomy: a population-based study.

BACKGROUND: At radical cystectomy (RC), continent urinary diversion (CUD) provides functional outcomes that most closely approximate that of a native bladder. We tested the hypothesis that patients treated at high RC caseload hospitals and/or by high RC caseload surgeons have higher CUD rates. METHODS: We identified 9,493 bladder cancer patients treated with RC between 1998 and 2007, within the Nationwide Inpatient Sample. Univariable and multivariable analyses tested the relationship between hospital and surgical caseload at RC, and CUD rate. Generalized estimating equations models were used to adjust for clustering among hospitals and surgeons. RESULTS: Only 8% of patients received a CUD at RC. The CUD rate was 5 vs. 7 vs. 13% for low versus intermediate versus high annual hospital caseload (AHC) tertiles (P < 0.001). The CUD rate was 6 vs. 10 vs. 16% for low versus intermediate versus high annual surgical caseload (ASC) tertiles (P < 0.001). In multivariable analyses, and after adjusting for clustering, ASC emerged as independent predictors of CUD rate (P < 0.001), while AHC failed to achieve the independent predictor status for the same end point (P ≥ 0.1). CONCLUSIONS: Our findings indicate that CUD is performed in a minority (8%) of RC patients. Surgical caseload represents an important determinant of CUD rate, while hospital caseload failed to achieve independent predictor status. Efforts should be made to optimize CUD rate a RC.

Timing and surgical management of neonatal testicular torsions.

BACKGROUND: The timing and surgical management of neonatal testicular torsions (NTTs) remain controversial, varying from immediate orchiectomy with empirical contralateral orchiopexy to expectant management with resulting atrophy of the affected testicle. The goal of the present study is to review the management of this entity at our institution. MATERIALS AND METHODS: A retrospective study of all patients with NTT from 1989 to 2007 was undertaken. The age, clinical presentation, investigation, management, and short- and long-term outcomes were noted. RESULTS: Forty-four patients were included. Most presented with a firm testicular mass, scrotal discoloration, and hydrocele (42), whereas a few presented with testicular atrophy (2). The median age at presentation was 1 day of age (range, 0-84 days), with NTT occurring on the right side in 22 patients and the left side in 20. Two patients (5%) had bilateral torsion at presentation. In 33 patients, the diagnosis was confirmed by Doppler ultrasonography, whereas 11 patients did not undergo any additional investigation. Surgical management included ipsilateral orchiectomy and contralateral orchiopexy (IOCO) (27), orchiopexy of the contralateral testis (CO) (7), bilateral orchiopexy (4), orchiectomy of the ipsilateral testis (1), orchiopexy of the ipsilateral testis (2), and observation (1). The 2 bilateral torsions underwent bilateral orchiectomy (2). The median age at surgery was 25 days (range, 1-912 days). Postoperative complications occurred in 8 patients (18%), mainly in those with IOCO (4) and CO (4) operated before 12 days of age, and included recurrent hydrocele (3), wound infection (2), urinary tract infection (1), and others (2). Upon follow-up, patients who underwent CO developed ipsilateral testicular atrophy (6). No patients were readmitted for recurrence of torsion or other complications. CONCLUSION: At our institution, the most frequent management of unilateral neonatal testicular torsions is IOCO or CO, but this carries an 18% complication rate, particularly if surgery is performed early. There seems to be no advantage to early intervention, and the need for orchiectomy is debatable because torsion leads to ipsilateral testicular atrophy. Contralateral orchiopexy done to decrease the incidence of bilateral asynchronous torsion should, at the very least, be deferred until the risks of anesthesia and surgery are improved, given its rarity. Given the fact that most patients underwent IOCO or CO, we cannot conclude which strategy is the best for neonatal testicular torsions. A prospective study is welcomed.

Comparative effects of hydroxocobalamin and cyanocobalamin on plasma homocysteine concentrations in end-stage renal disease.

End-stage renal disease (ESRD) is associated with marked hyperhomocysteinemia which is only partially corrected by folic acid and pyridoxine supplementation. We and others have reported that various forms of parenteral cobalamin reduce plasma total homocysteine (tHcy) concentrations of patients with ESRD substantially below the lowest levels attainable with folic acid. We here report a 16-week randomized controlled crossover trial which directly compared the Hcy-lowering effect of intravenous hydroxocobalamin (HC) with that of cyanocobalamin (CC). Folic acid- and vitamin B12-replete maintenance hemodialysis patients were randomly assigned to receive either 1 mg intravenous HC weekly for 8 weeks followed by CC for a further 8 weeks, or CC for 8 weeks followed by HC for 8 weeks. Hydroxocobalamin increased serum cobalamin concentrations 40-fold, whereas CC increased them only 10-fold, but both treatments reduced plasma tHcy concentrations similarly by 33% (P < .001). Crossover to the alternate form of the vitamin greatly affected the serum cobalamin concentration but was without further effect on the plasma tHcy concentration. These results confirm that weekly cobalamin injections lower plasma tHcy concentrations of hemodialysis patients well below the level attainable with folic acid. Hydroxocobalamin and CC are equipotent despite producing very different serum cobalamin concentrations.