The major factor influencing scintigraphic detection of abnormal parathyroid glands seems to be their size. However, false-negative results have been reported in large glands while some very small adenomas have been identified. Other factors can influence 99mTc-MIBI and 99mTc-Tetrofosmin uptake and therefore the accurate detection of hyperfunctioning glands depends also on these. Increases in both perfusion and functional activity and targeting of abundant mitochondria-rich oxyphil cells seem to be relevant mechanisms of uptake. A relationship has been observed between the intensity of focal uptake in the parathyroid glands and the cell cycle phases for patients with secondary hyperparathyroidism. Higher uptake grades correlated with the active growing phase, showing that scintigraphy accurately reflects the functional status of the hyperplastic parathyroid glands. Serum calcium levels may modify radiotracer kinetics by influencing the membrane potential. In addition, P-glycoprotein or multidrug resistance (MDR) associated protein expression may play an important role in the false-negative results of parathyroid scintigraphy. If the lipophilic cationic radiotracers used in parathyroid scintigraphy are transported by the same mechanism as the anticancer drugs, they will be quickly eliminated from the parathyroid glands containing P-glycoprotein or MDR-related protein expression and the uptake in images will be negative. In parathyroid glands with no P-glycoprotein or MDR-related protein expression, the radiotracers remain in the cells, making it easier to detect them by scintigraphy.

Double-phase parathyroid MIBI ((99m)Tc-sestamibi) was performed in 27 patients with secondary hyperparathyroidism (SPT). Focal areas of increased uptake were scored for intensity on a three-point scale. All patients underwent subtotal parathyroidectomy (SPTx), and a total of 78 glands were removed at operation. Blood was obtained from the jugular vein before and after SPTx to measure the parathyroid hormone (PTH) levels. The volume and weight of the glands were calculated. The tissue was divided, with one aliquot being used for cell cycle analysis. The nuclei were acquired by flow cytometry and analyzed using CELLEIT software. Cell viability was assessed by flow cytometry and analyzed with LYSIS II software. Positive MIBI uptake was observed in 88.8% of patients. Focal MIBI uptake of one, two, or three glands was observed in 6, 11, and 8 patients, respectively. All patients experienced an 86% decrease in PTH blood level after SPTx compared to that before excision. A correlation was found between the volume of glands and the blood levels of intact PTH (iPTH) (r = 0.5, p < 0.05). A positive correlation was observed between MIBI uptake and the iPTH levels before SPTx (p < 0.01) and between the uptake of MIBI in the parathyroid glands and the cell cycle phases; low-grade uptake correlated with the G(0) phase and higher uptake with G(2)+S phase (r = 7, p < 0.01). No correlation was observed between MIBI uptake and the weight of the glands. MIBI scintigraphy accurately reflects the functional status of the hyperplastic parathyroid glands: Higher uptake grades correlated with the active growth phase. MIBI uptake does not reveal parathyroid enlargement; rather, it identifies the presence of hyperfunctioning autonomous glands. SPTx and total parathyroidectomy with autografting (TPTx+A) are the most widely accepted surgical approaches for patients with SPT. Reoperation for recurrence is necessary in 6% to 15% of cases. MIBI is now considered to be the radionuclide of reference for parathyroid gland scanning, although it is widely accepted that it produces poor results when trying to detect hyperplastic glands.

Our new series of first-episode naive-schizophrenic patients (1) points out DAT dysfunction as an illness trait due to the significantly lower DAT binding in schizophrenic patients in comparison to healthy subjects; (2) supports the results of other authors who describe PS in never-treated patients; (3) confirms that [(123)I] FP-CIT does not allow us to predict which patients will develop parkinsonism due to the lack of differences between DIP and NoDIP patients; and (4) confirms a null effect of antipsychotics on DAT due to the lack of differences in [(123)I] FP-CIT before and after a 4-week-treatment period.

Objective. To evaluate the relationship between biochemical markers of bone turnover and bone scan indices of disease activity, as well as to analyze their variations based on skeletal involvement, in Paget's disease. Methods. Serum samples were obtained from 51 patients with Paget's disease to determine the levels of total alkaline phosphatase (total AP), bone alkaline phosphatase (bone AP), propeptide carboxyterminal of type I procollagen (PICP), propeptide aminoterminal of type I procollagen (PINP), osteocalcin, tartrate‐resistant acid phosphatase, and telopeptide carboxyterminal of type I collagen. Urine samples were analyzed for levels of hydroxyproline (HYP), pyridinoline (PYR), deoxypyridinoline (DPYR), C‐terminal telopeptide of type I collagen (CTx), and N‐terminal telopeptide of type I collagen (NTx). In addition, 2 semiquantitative scintigraphic indices, disease activity (AI) and disease extent (EI), were obtained. Pagetic skeletal locations were evaluated individually, with special attention to skull involvement. Results. All biochemical markers correlated with the AI and the EI. Serum PINP, bone AP, and total AP showed the highest proportions of increased values among the bone formation markers (94%, 82%, and 76%, respectively). Among the bone resorption markers, urinary NTx showed the highest proportion of increased values in patients with Paget's disease (96%), compared with PYR (69%), DPYR (71%), CTx (65%), and HYP (64%). In patients with mild disease activity, serum PINP was the marker with the highest proportion of increased values (71%). In contrast, serum PICP and urinary CTx were the most discriminative markers for skull involvement. Except for higher values for most of the biochemical markers of bone turnover in flat bones, no major differences in other skeletal locations were observed. Conclusion. The determination of serum PINP as a marker of bone formation and urinary NTx as a marker of bone resorption provided the best biochemical profile to ascertain the extent and activity of Paget's disease. In patients with skull involvement, serum PICP and urinary CTx were shown to be the most discriminative markers.

Our first-episode schizophrenic patients with and without DIP after short-term risperidone treatment have a decreased striatal DAT binding assessed with [(123)I] FP-CIT. This alteration could be related to the schizophrenic disease or may be secondary to the antipsychotic treatment.

Recent studies suggest that inhaled corticosteroids can adversely affect bone metabolism. The objective of this study was to evaluate the importance of these adverse effects in a case-control study.Bone mineral density (BMD) was measured in 48 asthmatic adults (15 males and 33 females) treated with inhaled steroids (beclomethasone or budesonide) and in 48 gender and age-matched healthy subjects at baseline and at 2 yrs. Vertebral BMD was measured by dual energy X-ray densitometry.Patients had been treated with a dose of 662±278 µg (range 300-1,000 µg) of beclomethasone dipropionate or budesonide for more than 1 yr (mean duration of treatment 10.6 yrs, range 1-16 yrs). Twenty four patients had needed 1-6 short courses of oral steroids and seven had received oral corticosteroids (mean daily dose 6.2 mg prednisone) for 2-15 yrs more than 4 yrs prior to the BMD measurements. During the follow-up, 14 patients required 1-3 short courses of oral steroids. There was no correlation either between inhaled corticosteroid doses or duration of treatment and BMD values. There were no significant differences in BMD baseline values between patients and healthy controls. BMD significantly decreased in both groups at 2 yrs, from 1.08±0.19 to 1.05±0.19 g·cm -2 (p=0.002) in asthmatics versus 1.12±0.17 to 1.09±0.18 g·cm -2 (p=0.008) in controls. There were no significant differences in BMD loss between patients and healthy controls. Furthermore, no differences were found in bone loss when pre-and postmenopausal women were compared with their healthy control counterparts. No differences in baseline BMD were found between patients who had received regular oral corticosteroid therapy or booster courses of oral corticosteroids and those who had not.Inhaled corticosteroid treatment at a mean dose of 662 µg·day -1 and sporadic booster courses of oral corticosteroids do not further increase bone mass loss with respect to that expected from natural bone mass loss.

Most of the Pagetic patients treated with tiludronate presented a long-term response, which persisted 2 yr after the end of treatment. The nadir response to treatment was observed 6 months after discontinuation of therapy whereas the relapse of disease activity was already observed 1 yr after the end of therapy and depended on both the baseline disease activity and the bone marker used in the evaluation.

Background and objectives: Hemodialysis needs an arteriovenous fistula (AVF) that may influence the structure and growth of nearby bone and affect bone mass measurement. The study analyzed the effect of AVF in the assessment of forearm bone mineral density (BMD) measured by dual energy x-ray absorptiometry (DXA) and examined its influence on the final diagnosis of osteoporosis.Design, setting, participants, & measurements: Forty patients (52 ؎ 18 yr) in hemodialysis program (12 ؎ 8 yr) with permeable AVF in forearm were included. Patients were divided in two groups (over and under 50 yr). BMD of both forearms (three areas), lumbar spine, and femur was measured by DXA. Forearm measurements in each arm were compared. Patients were diagnosed as normal only if all territories were considered nonpathologic and osteoporosis/osteopenia was determined by the lowest score found.Results: Ten patients were excluded and 30 patients were analyzed. BMD in the forearm with AVF was significantly lower than that observed in the contralateral forearm in both groups of patients and in all forearm areas analyzed. When only lumbar spine and femur measurements were considered, 70% of patients were nonpathologic and 30% were osteoporotic. However, inclusion of AVF forearm classified 63% as osteoporotic and a further 27% as osteopenic, leaving only 10% as nonpathologic.Conclusions: Forearm AVF affects BMD measurements by decreasing their values in patients with end-stage renal failure. This may produce an overdiagnosis of osteoporosis, which should be taken into account when evaluating patients of this type.