Day Of Nephrectomy Research Articles

Impact of postoperative intensive care unit utilization on postoperative outcomes in adults undergoing major elective noncardiac surgery

ObjectiveThere is a wide variation between hospitals with respect to rates of use of postoperative intensive care unit (ICU) after major noncardiac surgery. Whether ICU care improves patient-centered outcomes remains unknown. Days alive and out of hospital (DAH) is a novel patient-centered outcome that has been validated for surgical patients. We conducted a population-based cohort study to evaluate the association of hospital-level postoperative ICU use with DAH after select major elective noncardiac surgery. DesignHistorical cohort study. SettingAcute hospitals in Ontario, Canada. PatientsAdults aged ≥40 years who underwent lower gastrointestinal, peripheral arterial disease and nephrectomy surgery between 2006 and 2016. InterventionThe main exposure was admission to ICU within 24 h after surgery. MeasurementThe primary outcome was DAH at 30 days (DAH30) and secondary outcomes were DAH at 90 and 180 days (DAH90 and DAH180). Hospitals were ranked into quartiles based on the hospital-specific proportion of patients admitted to ICU within 24 h post-surgery. Descriptive statistics and hierarchical multivariable quantile regression modeling were used to assess the unadjusted and adjusted association of hospital-level ICU use with the primary and secondary outcomes for each surgical procedure. Main resultsThe cohort included 91,950 patients. Median DAH30 was 23 days for lower gastrointestinal resection, 24 days for peripheral arterial disease and 26 days for nephrectomy. Higher hospital-specific use of ICU use after surgery was not associated with improved DAH30, DAH90 or DAH180 for any surgical group. ConclusionsHospital-specific ICU admission practice showed no association with the patient-centered outcome of DAH in select elective major noncardiac surgical procedures.

Concordance of Pathologic Features Between Metastatic Sites and the Primary Tumor in Surgically Resected Metastatic Renal Cell Carcinoma

To evaluate the concordance of pathologic features in metastatic renal cell carcinoma (RCC) between the primary nephrectomy and metastasectomy specimens. Primary nephrectomy (n = 454) and matched metastasectomy specimens (n = 680) from patients treated between 1970 and 2009 for RCC were re-reviewed by 1 urologic pathologist in a blinded fashion. RCC histologic subtype, grade, coagulative necrosis, and the presence of sarcomatoid differentiation were compared between the primary and the metastatic tumor with kappa statistics. Concordance with the primary tumor was observed for subtype in 647 (95%, kappa = 0.71) of the metastases, for grade in 411 (60%, kappa = 0.35), necrosis in 460 (68%, kappa = 0.32), and sarcomatoid differentiation in 643 (95%, kappa = 0.60). Upgrading was observed in 100%, 63%, and 13% of patients with grades 1, 2, and 3 primary tumors, respectively (no patient had a grade 1 metastatic lesion). Metastatic tumors treated with metastasectomy within 30 days of nephrectomy (n = 145) had similar rates of concordant subtype, necrosis, and sarcomatoid differentiation to those undergoing metastasectomy beyond 30 days from nephrectomy (P >.05 for all), but had higher rates of concordant grade (71% vs 58%, P = .003). Pre-metastasectomy exposure to systemic targeted or immunotherapy was not associated with a change in concordance of histopathologic features. Among 454 surgically managed metastatic RCC patients, we observed a high degree of concordance for histologic subtype and sarcomatoid differentiation, and varying degrees of discordance for grade and coagulative tumor necrosis, between primary and metastatic tumors. Further investigation is warranted to understand the biologic and therapeutic implications of these observations.

MP57-07 WHO DIES FROM NEPHRECTOMY AND WHY DO THEY DIE? - THE IDENTIFICATION OF RISK FACTORS FOR PERIOPERATIVE DEATH FOLLOWING NEPHRECTOMY – A NATIONAL STUDY

INTRODUCTION AND OBJECTIVES: It is vital that patients and surgeons fully understand the risks of surgical interventions. Furthermore, only by analyzing adverse outcomes can a strategy for improving peri-operative care be implemented. The 2012 English national audit of nephrectomy outcomes gives an excellent opportunity to understand which patients and which interventions are at particularly high risk. METHODS: Members of the British Association of Urological Surgeons (BAUS) entered data online on 6042 nephrectomies performed in England in 2012. The dataset can be viewed at www.baus. org.uk/patients/surgical_outcomes. The information was analysed concentrating on deaths within 30 days of nephrectomy. RESULTS: 34 patients (0.6%) died within 30 days of nephrectomy. Headline results:

Upper Urinary Tract Laparoendoscopic Single-Site Surgery Based on a Novel Cost-Effective Reusable Platform

Several disposable platforms have been introduced for laparoendoscopic single-site (LESS) surgery. Besides technical issues, cost is one of the main limiting factors for their widespread use. We present our experience with LESS surgery for kidney pathologies using the first completely reusable LESS platform. We performed LESS kidney procedures in 29 patients including nephrectomy (18), partial nephrectomy (3), pyeloplasty (4), and renal cyst ablation (4). All procedures were performed using a completely reusable single-port device (X-Cone) with a simplified combination of standard and prebent instruments. We obtained perioperative and demographic data including a visual analog pain scale (VAS); complications were recorded using Clavien grading. Mean patient age was 49.31 years. Conversion to standard laparoscopy was necessary in one and addition of a needlescopic instrument in four cases. No open conversion was necessary. Intra- and postoperative complications occurred in two (Clavien II) cases. Mean operative time was 110, 90, and 89 minutes, and hospital stay was 4.9, 3.1, and 3.6 days for nephrectomy, partial nephrectomy, and pyeloplasty, respectively. Mean VAS was 2.13, 1.67, and 1.5 while blood loss was 81.3 mL, 140 mL, and 17.5 mL, respectively. There were no positive resection margins. LESS with a completely reusable platform is feasible for different upper urinary tract procedures yielding favorable functional and cosmetic results. A simplified combination of standard straight instruments and a single prebent grasper facilitates handling and shortens the learning curve. Reusable materials significantly reduce cost and may help to further adopt LESS surgery in surgical practice.

Laparoendoskopische Single-site-Chirurgie in der Urologie durch Einsatz eines wieder verwendbaren Systems

Many disposable platforms have been available for laparoendoscopic single-site surgery (LESS) for a long time. Besides technical challenges cost remains the limiting factor for the widespread use of LESS. We present our experiences with the first completely reusable LESS platform. We performed LESS procedures in 52 patients, including nephrectomy (n=18), adrenalectomy (2), partial nephrectomy (3), pyeloplasty (4), renal cyst ablation (4), pelvic lymphadenectomy (15) and lymphocele ablation (6). All procedures were carried out using a novel reusable single-port device (X-ConeR, Karl-Storz) with a simplified combination of standard and preformed instruments. Perioperative and demographic data including a visual analogue pain scale (VAS) were obtained. Complications were recorded using the Clavien classification. The mean age of the patients was 50.04 years. Conversion to standard laparoscopy was necessary in 3 cases and the additional use of a 3 mm needle instrument in 6 cases. There were no open conversions. Intraoperative and postoperative complications occurred in 3 (Clavien II in 2 and III in 1) cases. Mean operating time was 110, 90, and 89 min and hospital stay was 4.9, 3.1 and 3.6 days for nephrectomy, pelvic lymphadenectomy, and pyeloplasty, respectively. The mean VAS was 2.13, 1.07 and 1.5 while blood loss was 81.3 ml, 25.67 ml and 17.5 ml, respectively. The LESS technique with a completely reusable platform is applicable to various indications in urology yielding favorable functional and cosmetic results. This novel simplified combination of instruments facilitates handling and shortens the learning curve. Reusable materials may help to reduce cost leading to a wider acceptance of LESS.

Renal Tissue Damage After Experimental Pyelonephritis: Role of Antioxidants and Selective Cyclooxygenase-2 Inhibitors

To investigate the involvement of oxidative stress in the pathogenesis of acute pyelonephritis, and to evaluate the impact of meloxicam and/or L-carnitine in addition to conventional antibiotic treatment. A total of 48 Wistar rats were divided into 4 groups according to their treatment, which was started 1 day after inoculation of all rats with Escherichia coli (ATCC 25 922, 10(10) cfu/mL). Group 1 received only antibiotic treatment with ceftriaxone (50 mg/kg, IM). Groups 2 and 3 received L-carnitine (500 mg/kg, IM) and meloxicam (3 mg/kg, IM) in addition to conventional treatment, respectively. Group 4 received combination therapy (L-carnitine and meloxicam) in addition to the first group. Rats were killed 3 and 7 days after E. coli inoculation and underwent nephrectomy. Histologic determination of tubular atrophy, acute and chronic inflammation, interstitial fibrosis and biochemical determination of superoxide dismutase and catalase activity, total thiol content, total antioxidant capacity, and malondialdehyde and protein hydroperoxide levels were measured. Interstitial fibrosis (P = .06), chronic inflammation (P = .536), and tubular atrophy (P = 0.094) decreased in group 4 compared with the other groups, but there was a statistically significant decrease only in acute inflammation (P = .015). In addition, if the day of nephrectomy is considered, there was again a significant decrease in acute inflammation on day 7 compared with day 3 in groups 2, 3, and 4 (P = .002). Catalase significantly increased in group 2 (P = .029), group 3 (P = .02), and group 4 (P = .014), and decreased in group 1 (P = .012) in day 7. L-carnitine and meloxicam alleviated oxidative stress, probably by decreasing lipid peroxidation and enforcing antioxidant defense system. Acute renal inflammatory injury can be prevented much more effectively by combination therapy rather than by conventional therapy alone.

Renal Tissue Damage After Experimental Pyelonephritis: Role of Anti-Oxidants and Selective Cyclooxygenase-2 Inhibitors

Purpose Our aim was to examine the effect of anti-oxidant and selective cyclooxygenase-2 inhibitor therapy given adjunct to the conventional treatment of acute pyelonephritis on renal tissue damage. Material and Methods 48 wistar rats were divided into 4 groups according to their treatment modalities which were started one day after inoculation of all rats with 0.1 ml of E.Coli (ATCC 25922 1010 cfu/ml).First group received only antibiotic treatment with ceftriaxone (50 mg/kg, IM), second and third group received L-Carnitine (500 mg/kg, IM) and Meloxicam (.mg/kg, IM) in addition to the conventional treatment, respectively. Fourth group received combination therapy (L-Carnitine and Meloxicam) in addition to group one. 3 and 7 days after E.Coli inoculation rats were sacrificed and kidney samples were obtained for histologic determination of tubular atrophy, acute and chronic inflammation, interstitial fibrosis and biochemical determination of catalase activity (CAT), total antioxidant capacity (TAC) and malondialdehyde (MDA). Results Interstitial fibrosis (p:0.06), chronic inflammation (p:0.536) and tubular atrophy (p:0.094) decreased in group 4 compared to the other groups but there was statistically significant decrease only in acute inflammation (p:0.015). In addition,if the day of nephrectomy is considered, there was again a significant decrease in acute inflammation findings in day 7 compared to day 3 in group 2,3 and 4 (p:0.002). CAT significantly increased in group 2 (p:0.029),group 3 (p:0.02) and group 4 (p:0.014) and decreased in group 1 (p:0.012) in day 7. Conclusions Acute renal inflammatory injury can be prevented much more effectively by combination therapy than conventional therapy. This process is probably due to the prevention of free oxygen radical generation by anti-oxidants and inhibition of chemotaxis by selective cyclooxygenase-2 inhibitors. Our aim was to examine the effect of anti-oxidant and selective cyclooxygenase-2 inhibitor therapy given adjunct to the conventional treatment of acute pyelonephritis on renal tissue damage. 48 wistar rats were divided into 4 groups according to their treatment modalities which were started one day after inoculation of all rats with 0.1 ml of E.Coli (ATCC 25922 1010 cfu/ml).First group received only antibiotic treatment with ceftriaxone (50 mg/kg, IM), second and third group received L-Carnitine (500 mg/kg, IM) and Meloxicam (.mg/kg, IM) in addition to the conventional treatment, respectively. Fourth group received combination therapy (L-Carnitine and Meloxicam) in addition to group one. 3 and 7 days after E.Coli inoculation rats were sacrificed and kidney samples were obtained for histologic determination of tubular atrophy, acute and chronic inflammation, interstitial fibrosis and biochemical determination of catalase activity (CAT), total antioxidant capacity (TAC) and malondialdehyde (MDA). Interstitial fibrosis (p:0.06), chronic inflammation (p:0.536) and tubular atrophy (p:0.094) decreased in group 4 compared to the other groups but there was statistically significant decrease only in acute inflammation (p:0.015). In addition,if the day of nephrectomy is considered, there was again a significant decrease in acute inflammation findings in day 7 compared to day 3 in group 2,3 and 4 (p:0.002). CAT significantly increased in group 2 (p:0.029),group 3 (p:0.02) and group 4 (p:0.014) and decreased in group 1 (p:0.012) in day 7. Acute renal inflammatory injury can be prevented much more effectively by combination therapy than conventional therapy. This process is probably due to the prevention of free oxygen radical generation by anti-oxidants and inhibition of chemotaxis by selective cyclooxygenase-2 inhibitors.

Renal Tissue Damage After Experimental Pyelonephritis: Role of Anti-Oxidants and Selective Cyclooxygenase-2 Inhibitors

Purpose Our aim was to examine the effect of anti-oxidant and selective cyclooxygenase-2 inhibitor therapy given adjunct to the conventional treatment of acute pyelonephritis on renal tissue damage. Material and Methods 48 wistar rats were divided into 4 groups according to their treatment modalities which were started one day after inoculation of all rats with 0.1 ml of E.Coli(ATCC 25922 1010 cfu/ml).First group received only antibiotic treatment with ceftriaxone(50 mg/kg, IM), second and third group received L-Carnitine(500 mg/kg, IM) and Meloxicam(.mg/kg,IM) in addition to the conventional treatment, respectively. Fourth group received combination therapy(L-Carnitine and Meloxicam)in addition to group one. 3 and 7 days after E.Coli inoculation rats were sacrificed and kidney samples were obtained for histologic determination of tubular atrophy, acute and chronic inflammation, interstitial fibrosis and biochemical determination of catalase activity(CAT), total antioxidant capacity(TAC) and malondialdehyde(MDA). Results Interstitial fibrosis(p:0.06),chronic inflammation(p:0.536) and tubular atrophy(p:0.094) decreased in group 4 compared to the other groups but there was statistically significant decrease only in acute inflammation(p:0.015). In addition,if the day of nephrectomy is considered, there was again a significant decrease in acute inflammation findings in day 7 compared to day 3 in group 2,3 and 4(p:0.002). CAT significantly increased in group 2(p:0.029),group 3(p:0.02) and group 4(p:0.014) and decreased in group 1(p:0.012) in day 7. Conclusions Acute renal inflammatory injury can be prevented much more effectively by combination therapy than conventional therapy. This process is probably due to the prevention of free oxygen radical generation by anti-oxidants and inhibition of chemotaxis by selective cyclooxygenase-2 inhibitors.

Effect of simvastatin on proliferative nephritis and cell-cycle protein expression

Mesangial cell proliferation is important in subsequent mesangial matrix expansion in glomerular injury. Therefore, the regulation of mesangial cell proliferation may be critical in the treatment of glomerulonephritis. Inhibition of 3-hydro-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibits the production of mevalonate and has been shown to suppress proliferation in many cell types, including mesangial cells in vitro. It is expected that HMG-CoA reductase inhibitor may suppress mesangial cell proliferation and subsequent progression of glomerulonephritis. Recently, the tight relationship between cell-cycle regulatory protein expression and mesangial cell proliferation in experimental glomerulonephritis was demonstrated. The aim of the present study is to examine the effect of simvastatin, one of the HMG-CoA reductase inhibitors, on the glomerular cell proliferation and on the expression of CDK2 or p27Kip1 in mesangial cells in experimental glomerulonephritis in vivo. The effect of simvastatin on a rat mesangial proliferative glomerulonephritis induced by antithymocyte antibody (anti-Thy 1.1 GN) was studied. Administration of simvastatin or vehicle (for control GN) were started from two days before disease induction, and was continued to the day of nephrectomy. Nephrectomy was done at days 0, 2, 4, 7, 12 and 20 after disease induction. Immunohistochemistry for proliferating cells, macrophages, alpha-smooth muscle actin, type IV collagen and PDGF-B chain was performed, respectively, in addition to conventional periodic-acid Schiff staining. Double immunostaining for CDK2/OX-7 or p27Kip1/OX-7 was also done, respectively. There was no difference in the degree of the initial injuries between simvastatin-treated and control GN rats. The most pronounced feature of simvastatin-treated GN was the suppression of the early glomerular cell proliferation (about 70% of proliferation was suppressed at day 4). At day 4, alpha-smooth muscle actin expression was also decreased in simvastatin-treated GN rats. Inhibition of macrophage recruitment into glomeruli by simvastatin was also a prominent feature (about 30% decrease in the number of glomerular macrophages at day 2). Simvastatin significantly suppressed subsequent mesangial matrix expansion and type IV collagen accumulation in glomeruli. Although it might simply reflect the reduction in mesangial cells, glomerular PDGF-B chain expression was reduced. There was no significant difference in plasma lipids levels at day 2 and day 4. In vehicle-treated GN rats, the number of CDK2+/OX-7+ cells (CDK2-expressed mesangial cells) in glomeruli increased significantly from day 4 to day 7. Although simvastatin suppressed mesangial cell proliferation, the increase in the number of glomerular CDK2+/OX-7+ cells was also attenuated by simvastatin treatment. There was no difference in the number of p27Kip1+/OX-7+ cells (p27Kip1-expressed mesangial cells) in the glomerulus between vehicle-treated and simvastatin-treated GN rats. Simvastatin suppressed mesangial cell proliferation and subsequent matrix expansion, and macrophage infiltration into glomeruli in anti-Thy 1.1 GN rats. The antiproliferative effect of simvastatin in this model was also associated with the reduction of CDK2 expression in mesangial cells.

Laparoscopy for adult polycystic kidney disease: A promising alternative

The purpose of this study was to evaluate the efficacy of laparoscopy in managing patients with abdominal symptoms from autosomal dominant polycystic kidney disease (ADPKD). From April 1993 to July 1995, four patients with ADPKD underwent seven laparoscopic procedures: five cyst decortications were performed in two patients using a laparoscopic ultrasound unit and two laparoscopic nephrectomies were performed in two patients with end-stage renal failure. The mean operative time was 207 minutes for laparoscopic cyst decortication and 272 minutes for laparoscopic nephrectomy. The two nephrectomy specimens were 2,200 g and 1,750 g, respectively. The mean intraoperative blood loss was 85 mL. The patients resumed their oral intake within 10 hours after laparoscopic cyst decortication and within 16 hours after laparoscopic nephrectomy. The mean amount of parenteral analgesics required postoperatively was 12 mg morphine sulfate for cyst decortication and 30 mg morphine sulfate for nephrectomy. The mean hospital stay was 3 days for cyst decortication and 3.5 days for nephrectomy. The patients returned to their usual activities after an average of 2 weeks. Based on pain analog scales, all the patients have shown marked reduction in their symptoms (average, 90%) during an average follow-up period of 6.6 months. Laparoscopic cyst decortication and nephrectomy are effective minimally invasive treatment options for patients with adult polycystic kidney disease who are experiencing abdominal symptoms due to marked renal enlargement. We believe that by using a laparoscopic ultrasound unit, most renal cysts may be safely removed, and if need be, even “giant” kidneys can be removed laparoscopically. To the best of our knowledge, the two nephrectomy specimens in this study represent the largest kidneys removed laparoscopically to date and the first laparoscopic nephrectomies in ADPKD patients.

1,25(OH)2 vitamin D3 inhibits parathyroid cell proliferation in experimental uremia

Parathyroid cell proliferation and parathyroid hyperplasia are features of renal secondary hyperparathyroidism. Since parathyroids have recently been recognized as an important target for 1,25(OH)2D3, the effects of administration of variable doses of 1,25(OH)2D3 on ex vivo radiothymidine incorporation in the parathyroid glands, on parathyroid cell mitoses, on parathyroid weight, morphometric indices and on parathyroid protein/DNA ratio were examined in rats with uremia (subtotal nephrectomy; NX) or with calcium deficiency. 3H-thymidine incorporation (3 hr; 37 degrees C; PBS with 10 mmol glucose) was elevated in NX animals, that is, 204 +/- 51 dpm/micrograms DNA versus 96 +/- 28 in controls. In vivo pretreatment with 1,25(OH)2D3, either by intermittent i.p. injection or by osmotic minipump, dose-dependently decreased 3H-thymidine incorporation and parathyroid cell mitoses without affecting morphometric indices of parathyroid cells. Prophylactic administration (i.p.) of 1,25(OH)2D3, starting on the day of nephrectomy, prevented parathyroid hyperplasia (NX + 1,25(OH)2D3 0.84 micrograms tissue/g body wt vs. 1.25 micrograms in untreated NX and 0.54 in ad libitum fed controls), but 10 days of treatment beginning on the 21st day of uremia did not reverse existing hyperplasia (NX + 1,25(OH)2D3 1.5 micrograms/g body wt vs. 1.37 micrograms in untreated NX and 0.56 micrograms in ad libitum fed controls). The inhibitory effect was specific for 1,25(OH)2D3 and not imitated by Dexamethason. However, the effect was not specific for parathyroid hyperplasia of uremia, since similar inhibition of 3H-thymidine incorporation by 1,25(OH)2D3 was also observed in rats on low calcium diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in glomerular filtration rate, lithium clearance and plasma protein clearances in the early phase after unilateral nephrectomy in living healthy renal transplant donors.

1. Glomerular and tubular function was studied before and 2 months after unilateral nephrectomy in 14 healthy kidney donors by measurement of the clearances of 51Cr-labelled ethylenediaminetetra-acetate, lithium, beta 2-microglobulin, albumin and immunoglobulin G. 2. The glomerular filtration rate (GFR) of the kidney that remained in the donor rose from 45 +/- 10 (mean +/- SD) to 59 +/- 10 ml/min (P less than 0.01) 5 days after contralateral nephrectomy and remained at this level through the observation period. 3. The lithium clearance (CLi) of the remaining kidney rose from 11.6 +/- 3.7 to 20.5 +/- 8.2 ml/min (P less than 0.01) and remained significantly elevated throughout the observation period. 4. Absolute proximal fluid reabsorption rate (APR), which was estimated as GFR minus CLi, was unchanged 5 days after contralateral nephrectomy, but then rose gradually to reach significantly elevated levels after 4 weeks. 5. Fractional proximal reabsorption (FPR; APR/GFR) fell from 0.75 +/- 0.06 to 0.66 +/- 0.11 (P less than 0.01) but subsequently rose to levels not significantly decreased from normal. 6. Twenty-four hour fractional clearances of beta 2-microglobulin, albumin and immunoglobulin G rose markedly on the day of nephrectomy, peaked at 2-3 days and subsequently fell to moderately elevated levels. 7. Both the CLi and the plasma protein clearance studies demonstrate that the early response of the remaining kidney to contralateral nephrectomy in man is an increase in GFR, an unchanged APR and a fall in FPR. The proximal tubules thus initially handle the increased filtrate load by passing it on to more distal nephron segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Skeletal resistance to the calcemic action of parathyroid hormone in uremia: Role of 1,25(OH)2D3

Studies were carried out to investigate the role of 1,25(OH)2D3 in the skeletal resistance to the calcemic action of parathyroid hormone. The change in serum calcium after the intravenous infusion of 2 U of parathyroid extract (PTE)/kg body wt/hr for eight hours was evaluated in thyroparathyroidectomized (T-PTX) dogs before, and one, two and three days after, induction of uremia by bilateral ureteral ligation (11 dogs) or by bilateral nephrectomy (8 dogs). In another six nephrectomized and T-PTX dogs, 0.68 ug of 1, 25 (OH)2D3/day was given on the day of nephrectomy and for two days thereafter. Serum creatinine in each day of the study was not different among the three groups. The study also included the evaluation of the effect of sham operation (five dogs) and the administration of 1,25 (OH)2D3 to dogs with normal renal function (four dogs) on the calcemic response to PTE, as well as the reproducibility of such a response in the same animal. The results showed that 1) the calcemic response to PTE was markedly impaired after one day of bilateral ureteral ligation or nephrectomy, but the impairment was more severe after nephrectomy; 2) the calcemic response to PTE after two or three days of bilateral ureteral ligation was similar to that seen at one day after nephrectomy; 3) 1, 25 (OH)2D3 partially restored the calcemic response to PTE in the nephrectomized animals to levels similar to those seen after one day of bilateral ureteral ligation; 4) sham operation did not affect the response to PTE, and repeated infusion of PTE produced similar changes in the concentrations of serum calcium. The data indicate that (a) a deficiency of 1,25 (OH)2D3 is at least partly responsible for the skeletal resistance to the calcemic action of PTH in uremia; (b) uremia, per se, may also contribute to this phenomenon; and (c) the kidney after one day of complete bilateral ureteral ligation may still produce 1,25 (OH)2D3, but this ability is compromised after two days of ureteral obstruction.