A prospective study of dysgeusia and related symptoms in patients with multiple myeloma after autologous hematopoietic cell transplantation.

BACKGROUND: Dysgeusia is a common but understudied complication in patients undergoing autologous hematopoietic cell transplantation (auto-HCT). We assessed the feasibility of using chemical gustometry (CG) to measure dysgeusia and explored its associations with symptom burden, nutrition, chemotherapy pharmacokinetics (PK), and the oral microbiome. METHODS: We conducted a single-center, prospective feasibility study (NCT03276481) of patients with multiple myeloma undergoing auto-HCT. CG was performed longitudinally testing five flavors (sweet, sour, salty, bitter, umami) to calculate a total taste score (maximum score, 30). We measured caloric intake and patient-reported symptoms, assessing their correlation with oral microbiota composition and salivary and blood melphalan PK exposure. RESULTS: Among all 45 patients, 39 (87%) completed at least four (>60%) and 22 (49%) completed all six CG assessments. Median total CG scores remained stable over time but were lowest at day +7 (27, range 24-30) with recovery by day +100. Symptom burden was highest by day +10 (area under the curve, 2.9; range, 1.0-4.6) corresponding with the lowest median overall caloric intake (1624 kcal; range, 1345-2267). Higher serum/salivary melphalan levels correlated with higher patient-reported dysgeusia and lower caloric intake. Oral microbiota α-diversity was stable early and increased slightly by day +100. CONCLUSIONS: Assessment of dysgeusia by CG is feasible after auto-HCT. Most dysgeusia, symptom burden, and lowest caloric intake occurred during the blood count nadir. Higher melphalan concentrations correlated with more dysgeusia and poorer caloric intake. Future studies will aim to modulate melphalan exposure by PK-targeted dosing and characterize patient taste preferences to personalize diets for improved nutritional intake. LAY SUMMARY: Taste changes after cancer treatments are very common. We used chemical gustometry (taste testing) to study taste changes and to better understand why patients with multiple myeloma experience this symptom after autologous hematopoietic cell transplantation. We found that taste testing was feasible, taste changes peaked when blood counts were lowest, and most patients recovered their taste by 100 days after transplantation. Taste changes correlated with lower food intake and with higher levels of chemotherapy in the body. Future work will focus on using personalized chemotherapy doses to reduce taste changes and to match patients' individual taste preferences with their diets.

Impact of Toxicity on Survival for Older Adult Patients after CD34+ Selected Allogeneic Hematopoietic Stem Cell Transplantation.

Ex vivo CD34+ selection before allogeneic hematopoietic stem cell transplantation (allo-HCT) reduces graft-versus-host disease without increasing relapse but usually requires myeloablative conditioning. We aimed to identify toxicity patterns in older patients and the association with overall survival (OS) and nonrelapse mortality (NRM). We conducted a retrospective analysis of 200 patients who underwent CD34+ selection allo-HCT using the ClinicMACS® system between 2006 and 2012. All grade 3 to 5 toxicities by CTCAE v4.0 were collected. Eighty patients aged ≥ 60 years with a median age of 64 (range, 60 to 73) were compared with 120 patients aged < 60 years. Median follow-up in survivors was 48.2 months. OS and NRM were similar between ages ≥ 60 and <60, with 1-year OS 70% versus 78% (P = .07) and 1-year NRM 23% versus 13% (P = .38), respectively. In patients aged ≥ 60 the most common toxicities by day 100 were metabolic, with a cumulative incidence of 88% (95% CI, 78% to 93%), infectious 84% (95% CI, 73% to 90%), hematologic 80% (95% CI, 69% to 87%), oral/gastrointestinal (GI) 48% (95% CI, 36% to 58%), cardiovascular (CV) 35% (95% CI, 25% to 46%), and hepatic 25% (95% CI, 16% to 35%). Patients aged ≥ 60 had a higher risk of neurologic (HR, 2.63 [95% CI, 1.45 to 4.78]; P = .001) and CV (HR, 1.65 [95% CI, 1.04 to 2.63]; P = .03) toxicities but a lower risk of oral/GI (HR, .58 [95% CI, .41 to .83]; P = .003) compared with those aged < 60. CV, hepatic, neurologic, pulmonary, and renal toxicities remained independent risk factors for the risk of death and NRM in separate multivariate models adjusting for age and hematopoietic cell transplantation-specific comorbidity index. Overall, the toxicity of a more intense regimen is potentially balanced by the absence of toxicity related to methotrexate and calcineurin inhibitors in older patients. Prospective study of toxicities after allo-HCT in older patients is essential.

Effects of Late Toxicities on Outcomes in Long-Term Survivors of Ex-Vivo CD34+-Selected Allogeneic Hematopoietic Cell Transplantation.

The late adverse events in long-term survivors after myeloablative-conditioned allogeneic hematopoietic cell transplantation (HCT) with ex vivo CD34+ cell selection are not well characterized. Using the National Cancer Institute's Common Terminology Criteria for Adverse Events, version 4.0, we assessed all grade ≥3 toxicities from the start of conditioning to the date of death, relapse, or last contact in 131 patients who survived >1 year post-HCT, identifying 285 individual toxicities among 17 organ-based toxicity groups. Pretransplantation absolute lymphocyte count >.5 K/µL and serum albumin >4.0 g/dL were associated with a reduced risk of toxicities, death, and nonrelapse mortality (NRM), whereas serum ferritin >1000 ng/mL was associated with an increased risk of toxicities and NRM after 1 year. An HCT Comorbidity Index (HCT-CI) score ≥3 was associated with an increased risk of all-cause death and NRM, but was not associated with a specific increased toxicity risk after 1 year. Patients who incurred more than the median number of toxicities (n = 7) among all patients within the first year subsequently had an increased risk of hematologic, infectious, and metabolic toxicities, as well as an increased risk of NRM and inferior 4-year overall survival (OS) (67% versus 86%; P = .003) after the 1-year landmark. The development of grade II-IV acute graft-versus-host disease (GVHD) within the first year was associated with incurring >7 toxicities within the first year (P = .016), and also with an increased risk of all-cause death and NRM after 1 year. In multivariate models, cardiovascular, hematologic, hepatic, infectious, metabolic, neurologic, and pulmonary toxicities incurred after 1 year were independently associated with increased risk of death and NRM when adjusting for both HCT-CI and grade II-IV acute GVHD within the first year. One-year survivors of ex vivo CD34+ selection had a favorable 4-year OS of 77%, although the development of grade ≥3 toxicities after the first year was associated with poorer outcomes, emphasizing the fundamental importance of improving survivorship efforts that may improve long-term toxicity burden and outcome.

The Impact of Toxicities on First-Year Outcomes after Ex Vivo CD34+-Selected Allogeneic Hematopoietic Cell Transplantation in Adults with Hematologic Malignancies.

Factors that impact first-year morbidity and mortality in adults undergoing myeloablative allogeneic hematopoietic cell transplantation with ex vivo CD34+ selection have not been previously reported. We assessed all toxicities ≥ grade 3 from the start of conditioning to date of death, relapse, or last contact in 200 patients during the first year after transplantation, identifying 1885 individual toxicities among 17 organ-based toxicity groups. The most prevalent toxicities in the first year were of infectious, metabolic, hematologic, oral/gastrointestinal, hepatic, cardiac, and pulmonary etiologies. Renal complications were minimal. Grades II to IV and III and IV acute GVHD at day 100 were 11.5% and 3%, respectively. In separate multivariate models, cardiovascular, hematologic, hepatic, neurologic, pulmonary, and renal toxicities negatively impacted nonrelapse mortality (NRM) and overall survival during the first year. A higher-than-targeted busulfan level, patient cytomegalovirus seropositivity, and an Hematopoietic Cell Transplantation-Specific Comorbidity Index of ≥3 were associated with increased risk of NRM and all-cause death. Ex vivo CD34+ selection had a favorable 1-year OS of 75% and NRM of 17% and a low incidence of sinusoidal obstruction syndrome. These data establish a benchmark to focus efforts in reducing toxicity burden while improving patient outcomes.

Quantitation of Estradiol and Testosterone in Serum Using LC-MS/MS.

Adult and pediatric endocrinology and oncology often requires measuring serum estrogens and testosterone at very low concentrations. Conventional immunoassay methods often lack the required performance to meet this analytical need, and mass spectrometry techniques must be employed. Our aim was to develop a sensitive HPLC-MS/MS assay for both estradiol (E2) and testosterone (Te) in serum, utilizing commercially available calibrators and without the need for chemical derivatization. Serum samples, after the addition of an internal standard, are combined with a hexane:ethyl acetate extraction solution. The samples are vortexed, and the organic layer is decanted into a clean sample tube and evaporated to dryness under a stream of nitrogen. The samples are reconstituted in a water:methanol solution and separated chromatographically using a reversed-phase HPLC column. Subsequent mass spectrometry is performed using both positive ion mode for Te and negative ion mode for E2.

Measurement of the DNA alkylating agents busulfan and melphalan in human plasma by mass spectrometry.

Busulfan and melphalan are cytotoxic DNA alkylating agents that are used in many hematopoietic stem cell transplantation (HCT) conditioning regimens. We report the development of an assay using turbulent flow liquid chromatography (TFLC) and tandem mass spectrometry to simultaneously measure the concentration of busulfan (Bu) and melphalan (Mel) in human plasma. The method involves precipitating proteins in the plasma specimen with an organic solvent containing deuterated internal standards of both compounds. Following centrifugation, an aliquot of the supernatant was injected into the TFLC mass spectrometry system operated in the positive ion mode. The analytical measurement range for both compounds was 10-5000 ng/mL, and with validated dilutions the reportable range was extended to 25,000 ng/mL. Intra-day and inter-day (n = 20 day) precision studies showed a coefficient of variation (CV) of <7% at several concentrations across the measurement range. To determine accuracy recovery studies were performed at several concentrations spanning the measurement range. Recoveries for both compounds were between 98 and 103%. Additionally, busulfan was compared with an existing assay and showed excellent correlation. Experiments were conducted to rule out matrix effects, carryover and interference from endogenous substances. The validated clinically reportable range (CRR) and assay precision will allow this assay to be used clinically to monitor and adjust Mel and Bu levels to ensure better therapeutic outcomes and also to support clinical trials aimed at better defining therapeutic ranges.

Data from the analytical performance of the Abaxis Piccolo Xpress point of care analyzer in whole blood, serum, and plasma.

The objective of this study was to examine the analytical performance of 14 comprehensive metabolic panel analytes on the Abaxis Piccolo Xpress® Point of Care analyzer in serum, plasma, and whole blood. A method comparison was performed on all three specimen types intended for use on the Piccolo Xpress®: serum, heparinized plasma, and whole blood. This data is also presented in Murata et al. (2015) [1]. This article includes the actual Bland-Altman bias plots of the difference in results obtained for analytes in the comprehensive metabolic panel from the Abaxis Piccolo Xpress and the comparison instrument, the Ortho Vitros.

Data to support a simultaneous testosterone and estradiol assay in serum by LC-MS/MS.

A very sensitive LC-MS/MS assay was developed implementing a liquid-liquid extraction step followed by mass spectrometry which was operated in both positive and negative ion modes. The assay was calibrated with readily available commercial calibrators and compared with international reference standards. This data is also presented in "Sensitive Simultaneous Quantitation of Testosterone and Estradiol in Serum by LC-MS/MS without Derivatization and Comparison with the CDC HoSt Program" (Schofield et al., 2017). This article includes the comparison of the LC-MS/MS assay with a commonly available chemiluminescencent immunoassay for the quantitation of both estradiol and testosterone. In addition we show baseline separation of estradiol and testosterone from other structurally related and/or isobaric compounds that could potentially interfere with the assay. In addition, various calibrator materials were tested and compared with internationally-recognized reference materials.

Hypoadiponectinemia, dyslipidemia, and impaired growth in children with HIV-associated facial lipoatrophy.

OBJECTIVE: To compare growth, lipids and adipocytokines in HIV-positive children with and without lipoatrophy. PATIENTS: Eleven HIV-positive children with facial lipoatrophy, and 22 age- and sex-matched HIV-positive controls without signs of fat abnormality. METHODS: Clinical data including height, physical examination findings, medications, markers of viral control, cholesterol, and triglycerides were retrieved from the medical charts. Serum samples were analyzed for adiponectin, inflammatory markers, and high density lipoprotein cholesterol (HDL). RESULTS: Lipoatrophy was associated with higher triglycerides (330 vs 133 mg/dl, p = 0.0003), lower HDL (33 vs 48 mg/dl, p = 0.02), and a greater frequency of hypercholesterolemia (total cholesterol > 200 mg/dl; 64% vs 23%, p < 0.03). Adiponectin was 53% lower in patients with lipodystrophy (6.9 microg/ml vs 14.8 microg/ml, p = 0.005), however there was no difference in the inflammatory markers soluble TNFa receptor 2 or interleukin 6. Strikingly, despite similar BMI z-scores and virological control, lipoatrophic patients were shorter by 1 standard deviation score (p = 0.03). CONCLUSIONS: The presence of facial lipoatrophy in a child with HIV infection is a marker for significant metabolic derangements including dyslipidemia and hypoadiponectinemia, and suggests the need for careful growth evaluation.

Sensitive simultaneous quantitation of testosterone and estradiol in serum by LC-MS/MS without derivatization and comparison with the CDC HoSt program.

BACKGROUND: Very sensitive measurements of serum estrogens and testosterone are important in adult and pediatric endocrinology and immunoassays are known to lack the required performance at very low levels. Our aim was to develop a sensitive HPLC-MS/MS assay for both estradiol (E2) and testosterone (Te) in serum without the need for chemical derivatization and using commercially available calibrators. METHODS: Serum samples were prepared by the addition of internal standards followed by extraction using hexane:ethyl acetate. Chromatographic separation was achieved using a C18 column and mass spectrometry was performed in both positive and negative ion modes. RESULTS: The lower limits of quantitation (LLOQs) of E2 and Te were 5pg/mL and 1ng/dL, respectively. The analytical measurement range (AMR) for E2 was 5-600pg/mL and 1-1,170ng/dL for Te. Assay accuracy was determined both by comparison with a LC-MS/MS method performed at a national laboratory and the CDC HoSt program. Comparison with samples analyzed by both methods showed excellent correlation. Within-day (N=10) and between-day (N=20) CVs at concentrations spanning the AMR were less than 7% for both analytes. CONCLUSION: We have developed an accurate and highly sensitive assay to measure E2 and Te levels in serum by HPLC-MS/MS without chemical derivatization and using commercially available calibrators.

Topical tacrolimus for the treatment of secondary lymphedema.

Secondary lymphedema, a life-long complication of cancer treatment, currently has no cure. Lymphedema patients have decreased quality of life and recurrent infections with treatments limited to palliative measures. Accumulating evidence indicates that T cells play a key role in the pathology of lymphedema by promoting tissue fibrosis and inhibiting lymphangiogenesis. Here using mouse models, we show that topical therapy with tacrolimus, an anti-T-cell immunosuppressive drug, is highly effective in preventing lymphedema development and treating established lymphedema. This intervention markedly decreases swelling, T-cell infiltration and tissue fibrosis while significantly increasing formation of lymphatic collaterals with minimal systemic absorption. Animals treated with tacrolimus have markedly improved lymphatic function with increased collecting vessel contraction frequency and decreased dermal backflow. These results have profound implications for lymphedema treatment as topical tacrolimus is FDA-approved for other chronic skin conditions and has an established record of safety and tolerability.

Simultaneous Quantitation of Lamotrigine, Levetiracetam, 10-Hydroxycarbazepine, Topiramate, and Zonisamide in Serum Using HPLC-MS/MS.

Antiepileptic drugs (AEDs) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Over the past several decades some new AEDs, including lamotrigine (LTG), levetiracetam (LVA), oxcarbazepine (OXC), topiramate (TOP), and zonisamide (ZNS), have become widely used. This chapter describes a very simple and rapid liquid chromatography-tandem mass spectrometry method for simultaneous quantitation of LVA, ZNS, LTG, TOP, and MHD in human serum. The method requires a very small amount of serum (50 µL) for multiple drug measurements and has a total analysis time of 4 min that makes it well suited for routine clinical analysis of several drugs simultaneously. The imprecision (CVs) measured at various concentrations across the analytical measurement range (AMR) are less than 7% for all analytes. The AMR for each analyte is as follows: LVA (1-100 µg/mL), ZNS (0.8-80 µg/mL), TOP (0.5-50 µg/mL), and 0.6-60 µg/mL for LTG and MHD.

Quantitation of 25-OH-Vitamin-D2 and 25-OH-Vitamin-D3 in Urine Using LC-MS/MS.

Patients with significant proteinuria represent a unique population with respect to vitamin D status due to the urinary losses of vitamin D-binding protein (DBP) to which >99 % of circulating 25-hydroxy vitamin D (25(OH)D) is bound. Low serum concentrations of 25(OH)D have been found in children and adults with nephrotic syndrome (NS). However, previously described assays developed to quantify the magnitude of urinary loss are technically challenging. This chapter describes a simple and sensitive method to quantify 25(OH)D2 and 25(OH)D3 in urine specimens in a single analytical LC-MS/MS analysis. This assay is more sensitive than previously described radioimmunoassays and offers the ability to quantitate both forms of 25-hydroxy vitamin D. The assay involves no chemical derivitization, has a linear measurement range of 20-1500 pg/mL and displays imprecision (CVs) below 7 % at various concentrations across the analytical measurement range.

A Simple and Sensitive Method for Quantitative Measurement of Methylmalonic Acid by Turbulent Flow Chromatography and Tandem Mass Spectrometry.

A simple and sensitive method for the detection of methylmalonic acid in serum without derivatization has been developed. This method implements protein precipitation using methanol followed by additional sample clean up by turbulent flow liquid chromatography (TFLC). The sample was directly injected into the turbulent flow liquid chromatography tandem mass spectrometry system (TFLC-MS/MS) for online extraction followed by HPLC separation. The eluent was transferred to the mass spectrometer and ionized by heated electrospray negative ionization (HESI) and the analyte was quantified using a six-point calibration curve. The validated analytical measurement range (AMR) is 30-1,000 nMol/L. Dilutions of 10 and 200-fold were validated giving a clinical reportable range (CRR) of 30-200,000 nMol/L. The between-day and within-day imprecision values at concentrations spanning the AMR were less than 15%. This method was compared to an established LC-MS/MS method at a CLIA certified national reference laboratory and shows an excellent correlation with our TFLC-MS/MS method.

Development of an Assay for Methotrexate and Its Metabolites 7-Hydroxy Methotrexate and DAMPA in Serum by LC-MS/MS.

Methotrexate (MTX) is a folic acid antagonist that is widely used as an immunosuppressant and chemotherapeutic agent. After high-dose administration of MTX serum levels must be monitored to determine when to administer leucovorin, a folic acid analog that bypasses the enzyme inhibition caused by MTX and reverses its toxicity. We describe a rapid and simple turbulent flow liquid chromatography (TFLC) method implementing positive heated electrospray ionization (HESI) for the accurate and precise determination of MTX, 7-hydroxymethotrexate (7-OH MTX), and 4-amino-4-deoxy-N(10)-methylpteroic acid (DAMPA) concentrations in serum. MTX is isolated from serum samples (100 µL) after protein precipitation with a methanolic solution containing internal standard (MTX-D3) followed by centrifugation. The supernatant is injected into the turbulent flow liquid chromatography which is followed by electrospray positive ionization tandem mass spectrometry (TFLC-ESI-MS/MS) and quantified using a six-point calibration curve. For MTX, 7-OH MTX, and DAMPA the assays were linear from 20 to 1000 nmol/L. Dilutions of 10-, 100-, and 1000-fold were validated giving a clinically reportable range of 20 to 1.0 × 10(6) nmol/L. Within-day and between-day precisions at concentrations spanning the analytical measurement ranges were less than 10 % for all three analytes.

Analytical performance of the Abaxis Piccolo Xpress® point of care analyzer in whole blood, serum, and plasma.

OBJECTIVES: To examine the analytical performance of 14 comprehensive metabolic panel analytes on the Abaxis Piccolo Xpress® Point of Care analyzer in serum, plasma, and whole blood. DESIGN AND METHODS: Precision was evaluated by running two levels of control material over multiple days. Linearity was evaluated using material provided by the manufacturer and the College of American Pathologists (CAP) linearity surveys. Accuracy was evaluated by comparing the results from 60 patient specimens on the Piccolo Xpress® with the Ortho Vitros® 5600 analyzer. The method comparison was performed on all three specimen types intended for use on the Piccolo Xpress®: serum, heparinized plasma, and whole blood. Manufacturer suggested reference ranges for all 14 analytes were tested in serum and plasma specimens from 23 healthy volunteers. RESULTS: High precision (CV ≤ 10%) was noted for all the analytes. Linearity was found to span the clinically useful range for all analytes. The method comparison demonstrated minimal proportional bias and good correlation for most of the analytes in all three matrices tested. The only exceptions were for sodium and total CO2, for which either significant proportional bias and/or poor correlation was noted in all three matrices. Significant bias was noted for AST in serum as well as for total bilirubin in plasma and whole blood. CONCLUSION: The Piccolo Xpress® allows for the delivery of CMP results in a footprint small enough to be stored in a biological safety cabinet, while providing satisfactory performance for the majority of analytes.

Development and validation of a turbulent flow chromatography and tandem mass spectrometry method for the quantitation of methotrexate and its metabolites 7-hydroxy methotrexate and DAMPA in serum.

A rapid and simple turbulent flow liquid chromatography (TFC-LC) method implementing positive heated electrospray ionization (HESI) for the accurate and precise determination of methotrexate (MTX), 7-hydroxy methotrexate (7-OH MTX), and 4-amino-4-deoxy-N(10)-methylpteroic acid (DAMPA) concentrations in serum was developed. MTX was isolated from serum samples (100µL) after protein precipitation with methanol containing formic acid and internal standard (MTX-D3) followed by centrifugation. The supernatant was injected into the turbulent flow liquid chromatography which is followed by electrospray positive ionization tandem mass spectrometry (TFC-LC-MS/MS) and quantified using a six-point calibration curve. For MTX and DAMPA the assays were linear from 10 to 1000nmol/L and for 7-OH MTX from 20 to 2000nmol/L. Dilutions of 10, 100 and 1000-fold were validated giving a clinically reportable range of 10nmol/L to 5×10(5)nmol/L. Within-day and between-day precisions at concentrations spanning the analytical measurement ranges were less than 10% for all three analytes. MTX, DAMPA and 7-OH MTX were sufficiently stable under all relevant analytical conditions. No significant matrix effect was observed during the method validation. The TFC-LC-MS/MS MTX method was also compared with three other clinically validated MTX assays: a dihydrofolate reductase (DHFR) inhibition assay, an immunoassay based on fluorescence polarization and a previously developed LC-MS/MS assay.

Determination of reference intervals for serum total calcium in the vitamin D-replete pediatric population.

CONTEXT: Widespread vitamin D insufficiency raises concerns regarding the reliability of reference intervals for serum calcium. OBJECTIVE: We sought to determine the reference intervals for serum total calcium in pediatric subjects without vitamin D [25-hydroxyvitamin D [25(OH)D]] deficiency [20 ng/mL (50 nmol/L)]. DESIGN AND PARTICIPANTS: This was a retrospective study of laboratory data obtained from all patients at The Children's Hospital of Philadelphia from July 1, 2011, through June 30, 2012. Patients in the renal unit, the endocrine unit, or a critical care unit were excluded. Total serum calcium was determined using a colorimetric assay and serum 25(OH)D was determined by liquid chromatography tandem mass spectrometry. We ascertained 4629 subjects who had a serum 25(OH)D between 20 and 80 ng/mL (50-200 nmol/L) and a serum calcium level determined within 30 days of the 25(OH)D measurement. For comparison, we used data from an unselected cohort of patients (n = 106 220). RESULTS: Parametric analyses generated age-specific reference intervals for serum total calcium for each of several age groups (0-90 d old, 91-180 d old, 181-365 d old, 1-3 y old, 4-11 y old, and 12-19 y old). A two-way ANOVA with Tukey's correction showed significant differences between the lower limits of normal (P < .001) and the normal range (P < .001) but not for the upper limit of normal for these subjects compared with unselected subjects. Student's t tests revealed significant differences at all ages between calcium concentrations in those with 25(OH)D values between 20 and 30 ng/mL and those with 25(OH)D values between 30 and 80 ng/mL. CONCLUSIONS: These reference intervals refine previous normal ranges that likely included subjects with vitamin D deficiency.

A cross-sectional study of vitamin D and insulin resistance in children.

OBJECTIVE: Vitamin D deficiency is common and has been associated with several non-bone/calcium related outcomes. The objective was to determine the association between serum 25-hydroxyvitamin D (25-OH-D) and fasting glucose, insulin and insulin sensitivity in obese and non-obese children. PATIENTS/SETTING/DESIGN: Cross-sectional study of 85 children aged 4-18 years recruited from the local Philadelphia community and Sleep Center. MAIN OUTCOME MEASURES: Fasting blood glucose, insulin and 25-OH-D were measured. Insulin resistance was calculated using homeostasis model assessment (HOMA). Body mass index standard deviation scores (BMI-Z) and pubertal stage were determined. Multivariable linear regression was used to determine factors associated with decreased 25-OH-D and to determine the association of vitamin D with HOMA. RESULTS: Median 25-OH-D was 52 nmol/l (IQR 34-76). 26% of subjects were vitamin D sufficient (25-OH-D ≥75 nmol/l), 27% had intermediate values (50-75 nmol/l) and 47% were insufficient (25-50 nmol/l) or frankly deficient (<25 nmol/l). In the multivariable model, older age, higher BMI-Z and African-American race were all negatively associated with 25-OH-D; summer was positively associated with 25-OH-D. Lower 25-OH-D was associated with higher fasting blood glucose, insulin and HOMA after adjustment for puberty and BMI-Z. CONCLUSION: Low 25-OH-D, common in the paediatric population at risk for diabetes (older children, African-Americans, children with increasing BMI-Z) is associated with worse insulin resistance.