Multiplex LC-MS/MS for simultaneous determination of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D3, albumin, and vitamin D-binding protein with its isoforms: One-step estimation of bioavailable vitamin D and vitamin D metabolite ratio.

Bioavailable vitamin D and vitamin D metabolite ratio (VMR) have emerged as potential novel vitamin D markers. We developed a multiplex liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to determine all elements necessary for the calculation of bioavailable vitamin D and VMR, including 25-hydroxyvitamin D [25-(OH)D] and 24,25-dihydroxyvitamin D3 [24,25-(OH)2D3], VDBP and its isoforms, and albumin. Following separate reactions of hexane extraction and trypsin digestion, serum samples were analyzed using LC-MS/MS to measure 25-(OH)D3, 25-(OH)D2, 24,25-(OH)2D3, VDBP and its isoforms, and albumin. Analytical performances were assessed. Korean (n = 229), Arab (n = 98), White (n = 99) and Black American (n = 99) samples were analyzed. Bioavailable vitamin D and VMR were calculated. All target molecules were clearly separated and accurately quantified by LC-MS/MS. Analytical performances, including imprecision, accuracy, ion suppression, limit of quantification, linearity, and comparison with existing methods were within acceptable levels. The allele frequencies of VDBP isoforms in various races resulted similar to previously known values. The levels of bioavailable vitamin D were highest in White Americans and lowest in Black Americans. We have successfully developed a multiplex LC-MS/MS-based assay method that can simultaneously perform the measurement of all parameters needed to calculate bioavailable vitamin D and VMR. Our devised method was robust and reliable in terms of analytical performances and could be applied to routine clinical samples in the future to more accurately assess vitamin D status.

Factors associated with diffusely increased renal uptake of Tc-99m diphosphono-propanedicarboxylic acid on bone scintigraphy in patients with end-stage renal disease.

OBJECTIVE: We aimed to determine the factors contributing toward diffusely increased renal uptake on bone scintigraphy using technetium-99m (Tc-99m) diphosphono-propanedicarboxylic acid (DPD) in patients with end-stage renal disease. PATIENTS AND METHODS: One-hundred and forty-three bone scintigraphies, performed between June 2007 and July 2013, in 135 patients with chronic kidney disease were analyzed retrospectively, including 22 bone scintigraphies (15 patients; eight women; seven men) with glomerular filtration rates less than 15 ml/min/1.73 m. Patients with nephrocalcinosis were excluded. The clinical records of medication and underlying disease were reviewed retrospectively. The presence of renal artery calcification was visually estimated and the Hounsfield unit (HU) of renal parenchyma was measured by abdominal and pelvic nonenhanced computed tomography. RESULTS: Two patients underwent peritoneal dialysis and 13 underwent hemodynamic dialysis. Diffusely increased renal Tc-99m DPD uptake was observed on 15 of 22 (68%) bone scintigraphy images. Laboratory test results were not significantly different between the patients with or without increased renal uptake. A history of inflammatory conditions or antibiotic administration did not correlate with kidney visualization. The significant factor for diffuse renal tracer uptake on multivariate analysis was renal artery calcification (odds ratio: 18.42; 95% confidence interval: 2.01-79.43; P<0.001). The mean HU values were significantly higher in patients with diffuse renal tracer uptake (P=0.04) and renal artery calcification (P=0.02). CONCLUSION: Small renal arteriolar calcification and a higher HU value of renal parenchyma could be associated with diffusely increased renal Tc-99m DPD uptake in patients with end-stage renal disease.

Capsulotomy Size Affects Hip Joint Kinematic Stability.

PURPOSE: To evaluate the effect of capsulotomy size and subsequent repair on the biomechanical stability of hip joint kinematics through external rotation of a cadaveric hip in neutral flexion. METHODS: Eight fresh-frozen cadaveric hip specimens were used in this study. Each hip was tested under torsional loads of 6 N·m applied by a servohydraulic frame and transmitted by a pulley system. The test conditions were (1) neutral flexion with the capsule intact, (2) neutral flexion with a 4-cm interportal capsulotomy, (3) neutral flexion with a 6-cm capsulotomy, and (4) neutral flexion with capsulotomy repair. Soft tissue was retained during all interventions. Measures indicating joint kinematics (range of motion [ROM], hysteresis area [HA], and neutral zone [NZ]) were obtained for each condition. RESULTS: For all hip specimens, the average ROM, HA, and NZ were calculated relative to the intact capsular state (100%) and expressed in terms of percentage (± SD). The findings for ROM were as follows: intact, 100%; 4 cm, 107.42% ± 5.69%; 6 cm, 113.40% ± 7.92%; and repair, 99.78% ± 3.77%. The findings for HA were as follows: intact, 100%; 4 cm, 108.30% ± 9.30%; 6 cm, 115.30% ± 13.92%; and repair, 99.47% ± 4.12%. The findings for NZ were as follows: intact, 100%; 4 cm, 139.61% ± 62.35%; 6 cm, 169.25% ± 78.19%; and repair, 132.03% ± 64.38%. Statistically significant differences in ROM existed between the intact and 4-cm conditions (P = .039), the intact and 6-cm conditions (P < .0001), the 4-cm and repair conditions (P = .033), and the 6-cm and repair conditions (P < .0001). There was no statistically significant difference between the intact and repair conditions (P > .99) or between the 4- and 6-cm conditions (P = .126). CONCLUSIONS: Under laboratory-based conditions, larger-sized capsulotomies were accompanied by increases in all 3 measures of joint mobility: ROM, HA, and NZ at time zero. Complete capsular closure effectively restored these measures when compared with the intact condition. CLINICAL RELEVANCE: Cadaveric models consisting of the hip joint with surrounding soft tissue were used under laboratory testing conditions to investigate potential iatrogenic joint instability resulting from expansive capsulotomies, showing that complete capsular closure leads to reconstitution of original joint stability properties at time zero.

Evaluating the quality of Internet information for femoroacetabular impingement.

PURPOSE: The Internet has become a ubiquitous source of medical information for both the patient and the physician. However, the quality of this information is highly variable. We evaluated the quality of Internet information available for femoroacetabular impingement (FAI). METHODS: Four popular search engines were used to collect 100 Web sites containing information on FAI. Web sites were evaluated based on authorship, various content criteria, and the presence of Health On the Net Code of Conduct (HONcode) certification. By use of a novel evaluation system for quality, Web sites were also classified as excellent, high, moderate, poor, or inadequate and were subsequently analyzed. Web sites were evaluated as a group, followed by authorship type, by HONcode certification, and by quality level. RESULTS: Of the Web sites, 73 offered the ability to contact the author, 91 offered a considerable explanation of FAI, 54 provided surgical treatment options, 58 offered nonsurgical treatment options, 27 discussed possible complications, 11 discussed eligibility criteria, 31 discussed rehabilitation, 67 discussed a differential diagnosis, and 48 included peer-reviewed citations. We categorized 40 Web sites as academic, 33 as private, 9 as industry, 9 as public education, and 9 as blogs. Our novel quality evaluation system classified 16 Web sites as excellent, 18 as high, 17 as moderate, 18 as poor, and 31 as inadequate. Only 8% of all evaluated Web sites contained HONcode certification. CONCLUSIONS: We found that the quality of information available on the Internet about FAI was dramatically variable. A significantly large proportion of Web sites were from academic sources, but this did not necessarily indicate higher quality. Sites with HONcode certification showed as much variability in quality as noncertified sites. CLINICAL RELEVANCE: This study increases clinician competence in the available Internet information about FAI and helps them to confidently guide patients to formulate appropriate medical decisions based on high-quality information.