Bone Nanomechanical Properties and Relationship to Bone Turnover and Architecture in Patients With Atypical Femur Fractures: A Prospective Nested Case-Control Study

Atypical femur fractures (AFFs) are well‐established serious complication of long‐term bisphosphonate and denosumab therapy in patients with osteopenia or osteoporosis. To elucidate underlying mechanism(s) for the development of AFF, we performed a nested case‐control study to investigate bone tissue nanomechanical properties and prevailing bone microstructure and tissue‐level remodeling status as assessed by bone histomorphometry. We hypothesized that there would be differences in nanomechanical properties between patients with and without AFF and that bone microstructure and remodeling would be related to nanomechanical properties. Thirty‐two full‐thickness transiliac bone biopsies were obtained from age‐ and sex‐matched patients on long‐term bisphosphonate therapy with (n = 16) and without an AFF (n = 16). Standard histomorphometric measurements were made in each sample on three different bone envelopes (cancellous, intracortical, and endosteal). Iliac bone wall thickness was significantly lower on all three bone surfaces in patients with AFF than in those without AFF. Surface‐based bone formation rate was suppressed similarly in both groups in comparison to healthy premenopausal and postmenopausal women, with no significant difference between the two groups. Nanoindentation was used to assess material properties of cortical and cancellous bone separately. Elastic modulus was higher in cortical than in cancellous bone in patients with AFF as well as compared to the elastic modulus of cortical bone from non‐AFF patients. However, the elastic modulus of the cancellous bone was not different between AFF and non‐AFF groups or between cortical and cancellous bone of non‐AFF patients. Resistance to plastic deformation was decreased in cortical bone in both AFF and non‐AFF groups compared to cancellous bone, but to a greater extent in AFF patients. We conclude that long‐term bisphosphonate therapy is associated with prolonged suppression of bone turnover resulting in altered cortical remodeling and tissue nanomechanical properties leading to AFF. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Tumor Induced Osteomalacia - Long Term Medical Treatment When Surgery Is Risky

Introduction: Tumor induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by bone pain, muscle weakness and fractures caused by production of a phosphaturic factor by rare mesenchymal bone or soft tissue tumors that causes isolated renal phosphate loss and osteomalacia. Low phosphate (iP), high bone alkaline phosphatase (BAP), and normal or low 125 dihydroxy D, are salient biochemical findings. Fibroblast derived growth factor (FGF 23) may be high or inappropriately normal. Gallium-68 Dotatate (DoT) imaging has become the imaging method of choice. Long term medical management may be required when removal of the tumor is risky or not feasable. Case Report: 65 yr old woman with carcinoid tumor of the right lung and a bony lesion in the T3 vertebral body diagnosed with TIO. She was initially screened for osteoporosis after traumatic rib fractures. Bone scan and SPECT-CT revealed numerous foci of increased uptake. She had elevated alkaline phosphatase 186 IU/L (0–140) and PTH 83 pg/ml (15–65) with a low phosphate 1.5 mg/dl (2.5–4.5), along with normal FGF23 level 102 RU/ml Ref Range < + 180 RU/ml. DoT and PET CT imaging for TIO evaluation showed a foci of increased uptake right lower lobe of her lung, and “osseous metastatic disease” in the right scapula, vertebral body, iliac, and pubic ramus. Sclerosis of T3 vertebral body was noted in the area of intense Gallium Dotatate uptake. Transbronchial excision of the lesion showed a well differentiated neuroendocrine carcinoma. Chromogranin A and 24 hour urine for 5HIAA were normal. She responded well to medical therapy with oral phosphate, calcium and calcitriol. Follow up, DoT and FDG PET showed persistent intense uptake in the sclerotic lesion on T3 vertebral body, while the rest of the hot spots resolved. Sclerotic T3 lesion is likely the primary lesion that is responsible for the TIO. Neuroendocrine tumor of the lung may be a mere association. Biopsy of the T3 lesion was not feasible and excision was considered risky to the patient.

Discussion: Our case illustrates that awareness is the key to early diagnosis of TIO. FGF 23 in some TIO cases may be inappropriately normal in commercial assays and even in research labs. Measurement of fibronectin 1 (FN1) and FGF receptor 1 fusion gene which is noted in up to 60% of tumors are not commercially available. While DoT and PET CT are imaging modality of choice, CT and MRI may be useful to define the anatomy of the lesion. Long term medical management may be necessary when removal of primary lesion is not possible or risky. Most tumors are benign while some may prove to be malignant.

UTILITY OF AFIRMA GENE EXPRESSION CLASSIFIER FOR EVALUATION OF INDETERMINATE THYROID NODULES AND CORRELATION WITH ULTRASOUND RISK ASSESSMENT: SINGLE INSTITUTIONAL EXPERIENCE

Objective: We assessed our experience with Afirma gene expression classifier (GEC) combined with sono-graphic risk assessment, using both the American Thyroid Association (ATA) and the Thyroid Imaging Reporting and Data System (TI-RADS) in evaluating indeterminate thyroid nodules. Methods: We identified 98 patients with 101 nodules who had a second fine needle aspiration biopsy (FNA) between January 1, 2014, and September 30, 2017, and sent to Veracyte for cytopathology and subsequent Afirma GEC testing. A second FNA biopsy was performed if the initial cytopathology was either Bethesda III or IV (n = 94) or nondiagnostic (n = 7). We correlated cytopathology, histopathology, and Afirma GEC results with sonographic risk assessment using both the ATA system and TI-RADS. Results: The mean age of the cohort was 57.4 ± 12.3 years; 84% women and 60% white. Repeat FNA was benign in 51 of 101 nodules, and of the remaining 50 nodules, 18 (36%) were GEC-benign and 32 (64%) GEC-suspicious. Eighteen of the 32 GEC-suspicious nodules underwent surgery with the following results: 7 benign (39%), 1 follicular thyroid carcinoma (6%), 6 follicular variant of papillary thyroid cancer (33%), and 4 noninvasive follicular tumor with papillary-like nuclear features (22%). The malignancy rate among the surgical cohort was 39% (without noninvasive follicular tumor with papillary-like nuclear features [NIFTP]) and 61% (with NIFTP) and about 50% and 20% of this group scored in the high suspicion category by ATA and TR5 by TI-RADS, respectively. Conclusion: Afirma GEC was useful in avoiding surgery in one-third of indeterminate nodules and performed similarly to ATA and TI-RADS. However, the use of echogenicity in scoring may underestimate the risk of malignancy in patients with indeterminate nodules. Abbreviations: ATA = American Thyroid Association; AUS = Atypia of Undetermined Significance; FLUS = Follicular Lesion of Undetermined Significance; FN = follicular neoplasm; FNA = fine needle aspiration; FTC = follicular thyroid cancer; FVPTC = follicular variant of papillary thyroid cancer; GEC = Gene Expression Classifier; ND = nondiagnostic; NIFTP = noninvasive follicular tumor with papillary-like nuclear features; TI-RADS = Thyroid Imaging Reporting and Data System; TR = TI-RADS.

MON-393 Neuroblastoma Masquerading as Pheochromocytoma

Peripheral neuroblastic tumors (PNTs) are a group of tumors arising from sympathetic ganglion cells. It is a malignancy of childhood and rare in adults. The incidence in adulthood is only 0.12-0.2 cases per million per year. A 37 year old male presented with acute exacerbation of low back pain which started months prior to admission. MRI of the lumbar spine revealed a 3.6 x 3.4 cm lobulated heterogeneous mass-like lesion involving his right adrenal gland therefore, endocrinology evaluation was requested but not completed. He was a non-smoker without any significant past medical or surgical history and was not on any medications. On examination, He was normotensive and appeared to be in moderate distress. He had tenderness over the right sacroiliac joint. His renal and liver functions were normal. Serum metanephrines were normal however, normetanephrines were elevated to 501 pg/mL (< or = 148 pg/mL). Urine normetanephrines were 3,192 ug/day (88-444 ug/d), Urine volume of 3 L, total metanephrines of 3,342 ug/d (140-785 ug/d). Chromogranin A was 1,379 ng/mL (0-95 ng/mL). DHEAS, 17- hydroxyprogesterone, androstendione, and ACTH were normal. CT of his abdomen and pelvis with contrast showed a lobular heterogeneous mass involving the right adrenal gland with an increased size of 4.9 x 4.3 cm measuring 55 Hounsfield Units (HU). Right iliac core needle biopsy was done to evaluate his diffuse osseous metastasis which showed crush artifact, with positive chromogranin and synaptophysin staining. Right posterior pelvic crest lesion excision biopsy showed primitive small round cell neoplasm with neuroendocrine features, favoring an adult type neuroblastoma confirmed by immunohistochemical staining. He received chemotherapy and radiation and prior to debulking surgery, we initiated doxazosin. Surgery revealed a 6 cm neuroblastoma with extraadrenal extension. Iodine 123-metaiodobenzylguanidine (I-123 MIBG) showed extensive diffuse osseous metastatic disease. His catecholamines declined after surgery. Bone marrow (BM) involvement was noted and he underwent bone marrow transplantation with clinical improvement six months post-transplant. Although pediatric neurblastoma has a 91% survival rate, rates progressively decline to 40% in adults aged 25-64 years. Metastatic dissemination occurs in up to 40% of adults, mainly in the bone and BM as seen in our case therefore, adults should have a BM assessment upon diagnosis. Main issue is differentiation between PNTs and pheochromocytoma, that might be challenging due to variable imaging characteristics of PNTs and secretion of catecholamines in up to 70% of PNTs. On the other hand, catecholamines can be used as tumor markers for monitoring. Majority of adult PNTs are high-risk tumors with poor prognosis. No guidelines for adult management exists due to the rarity of the disease.

SAT-522 Markers of Mineral Homeostasis and Bone Turnover in Patients Presenting with Acute Hip Fractures

We previously reported on the very low rate of bone density assessment and vitamin D nutritional (VDN) status among 135 patients presenting with proximal hip fractures (ENDO-2018). It is generally assumed that bone turnover increases soon after a fracture, particularly after a major fracture such as hip. However, very little data exists on bone turnover markers (BTM) immediately after a hip fracture. In addition, it is unclear if the BTMs are related to prevailing VDN and parathyroid function. As part of ongoing project we assessed these characteristics in a larger sample (162), and further evaluated the indices of mineral homeostasis (as assessed by serum PTH and 25-OHD levels), and bone turnover (as assessed by serum CTX and bone specific alkaline phosphatase (BSAP); commonly used markers of bone resorption and formation respectively, in clinical practice. 162 patients were admitted with proximal femur fractures over 5y (1/1/2011 to 12/31/2016). The electronic health records (EHR) of 162 patients were reviewed to determine the rate of BMD testing, VDN, parathyroid function and BTMs. There were 112 women (69%) and 72 (44%) Caucasians with a mean age 78.6 ± 12.4y (range 49-98y). Mean 25-OHD was 22.6 ±12.9 ng/ml, and PTH was 61.1 ± 37.9 pg/ml. Mean serum CTX was 481 ± 241 mmol/mol and BSAP was 20.2 ± 14.6. Prevalence of vitamin D deficiency (<20ng/ml) was 44%, insufficiency (<30ng/ml) was 36%, and only 20% had optimal VDN. Serum PTH >70pg/ml in 25% (17/69), of whom 8 had 25-OD <20 ng/ml. By contrast, 42% (22/52) patients with serum PTH <70 pg/ml had a serum 25-OHD <20 ng/ml; the difference in vitamin D insufficiency was similar between the two groups of patients with and without hyperparathyroidism. Serum CTX was <300 mmol/mol in 25% (21/80) patients, which we considered as low bone turnover, and the mean BSAP in these patients was 13.4 ± 4.9 µg/L. Sixteen patients (20%) had serum BSAP >22 µg/L, all of whom had serum CTX >300 mmol/mol, which we considered as high bone turnover. The remaining 55% had high serum CTX 300-600 mmol/mol and the mean BSAP in these patients was 16.2 ± 7.9 µg/L. In a sub-set of 51 patients with BMD, osteopenia was seen in 13% using spine and 12% using femoral neck T-Scores, and osteoporosis in 9% using spine and 14% using femoral neck T scores. Neither spine nor femoral neck BMD correlated with VDN, PTH, or BTMs. Conclusions: Despite acute major fracture 26% have low bone turnover as assessed by BTMs. Only 25% had PTH >70 pg/ml that was not related to the prevailing VDN or renal function, but was related to age. High bone turnover was present in 74%, but was not related to PTH level or VDN. This is the first and most comprehensive study of mineral and skeletal homeostasis in a large sample of patients with hip fracture. Considering the large variation in BTMs, our findings may have therapeutic (antiresoprtive/anabolic) implications. Further studies are need to either confirm or refute our observations.

SAT-507 Pneumocystis Carinii Pneumonia: A Rare Cause of Granulomatous Hypercalcemia

Pneumocystis Carinii pneumonia (PCP) is a well-known complication of immunosuppression. Scattered case reports have linked PCP and its ability to induce a granulomatous response to hypercalcemia. PCP related hypercalcemia appears to be resistant to standard therapy. We report a case of hypercalcemia that preceded PCP and continued to worsen during the course of infection. A 63y man with renal transplant for polycystic kidney disease one year prior, presented with a three week history of fatigue, cough and chills. Patient was hypoxic and CT of the thorax revealed diffuse ground glass opacities. He was started on empiric therapy for PCP with intravenous methylprednisolone, clindamycin, and primaquine. Laboratory studies revealed a serum calcium of 12 mg/dl (baseline 9.2mg/dl, reference range 8.6-10.4 mg/dl) and creatinine of 3.23 mg/dl, which rose from a baseline value of 1.6 mg /dl. The patient’s bronchoalveolar lavage confirmed PCP. Endocrinology was consulted for evaluation of hypercalcemia. Further investigations revealed a suppressed PTH of 15 pg/ml from a baseline of 97 pg/ml (reference range 15-65pg/ml) post-transplant, 25-hydroxyvitamin D level of 30 ng/ml (reference range >20 ng/ml ), and 1,25-dihydroxyvitamin D(1,25D) level was elevated (>156 pg/ml; reference range 20-79 pg/ml). A diagnosis of 1,25D mediated hypercalcemia was made, intravenous fluids started and high dose steroids continued. Serum calcium levels improved transiently but subsequently rose to a peak level of 13.5 mg/dl. Ketoconazole 200 mg every 8hrs was started to reduce 1,25D production. Serum calcium remained high despite a reduction in 1,25D level (33 pg/ml). Bisphosphonates therapy was considered unsafe because of decreased GFR. Therefore, denosumab 30mg was administered, which resulted in decrease in serum calcium level to 10.3 mg/dl by day 19. Improvement of hypercalcemia correlated with improvement of PCP and renal function. Patient was discharged home after completing the 21 day course of treatment for PCP. Five weeks later, serum calcium stayed normal with an elevated PTH of 153 pg/ml and 1,25D level of 20 pg/ml. Hypercalcemia heralding PCP infection has been reported in the literature. Elevated calcium of 10.6 mg/dl was present one month prior to our patient’s hospitalization around the time of onset of his symptoms. Of the 19 cases of hypercalcemia due to PCP infection, 5 had hypercalcemia that preceded PCP infection by few weeks. The gold standard for diagnosis of PCP involves identification of the organism in induced sputum or bronchoalveolar lavage specimen. Measurement of serum 1,3-β-d-Glucan, which has high sensitivity, may be used as a screening tool in the right clinical setting such as our patient with immunosuppression and hypercalcemia to diagnose PCP at an earlier stage. We believe that hypercalcemia in a patient with immunosuppression should alert the possibility of PCP infection.

Bone Structure and Turnover Status in Postmenopausal Women with Atypical Femur Fracture After Prolonged Bisphosphonate Therapy

Atypical femur fracture (AFF), a serious complication of long-term bisphosphonate therapy, is usually preceded by an incomplete fracture appearing on the lateral femur. AFF is most likely the result of severely suppressed bone turnover (SSBT). However, the differences in bone structure and turnover between patients with incomplete and complete AFF remain unknown. We examined trans-iliac bone biopsies from 12 white postmenopausal women with AFF (incomplete = 5; complete = 7) on BP therapy of >5 years and 43 healthy white premenopausal women. Histomorphometric measurements were performed separately in cancellous, intracortical and endosteal envelopes. Of the 43 histomorphometric measurements on 3 difference bone surfaces (cancellous, intracortical and endosteal), only 2 bone resorption variables (Oc.S/BS and Oc.S/NOS) on the endosteal surface were significantly lower in patients with complete AFF than those with incomplete AFF. Compared to healthy premenopausal women, the trabecular bone volume, thickness and number were all significantly lower in patients with AFF. The dynamic bone formation variables in patients with AFF were significantly reduced on all bone surfaces. The likelihood of a biopsy with no tetracycline labeling was significantly higher in AFF patients than in healthy premenopausal women. Based on these results, we conclude that there are no significant differences in bone turnover between patients with incomplete and complete AFF, suggesting that the suppression of bone turnover had already existed in the femur with incomplete AFF. Compared to healthy premenopausal women, bone turnover is similarly suppressed in patients with either type of AFF.

Sclerostin: recent advances and clinical implications

PURPOSE OF REVIEW

Discovery of the Wnt signaling pathway and understanding the central role of osteocyte in skeletal homeostasis have been the major advances in skeletal biology over the past decade. Sclerostin, secreted mainly (but not exclusively) by osteocytes, has emerged as a key player in skeletal homeostasis. This review highlights the most relevant recent advances.

RECENT FINDINGS

Sclerostin by inhibiting Wnt signaling pathway decreases bone formation and osteoblast differentiation and promotes osteoblast apoptosis. Ability to measure serum sclerostin levels better clarified the role of sclerostin in various physiologic and pathologic states. Early clinical trials with antibodies to sclerostin have produced robust increases in bone mineral density, and fracture prevention trials are underway.

SUMMARY

Since the discovery of Wnt signaling pathway and sclerostin's association with high bone mass, there has been a remarkable progress. Clinical trials with fracture endpoints, already underway, should expand osteoanabolic therapeutic horizon in the very near future. Measurement of sclerostin levels in a number of conditions has advanced our knowledge about pathophysiology of skeletal and nonskeletal disorders in an altogether new light.

Acromegaly and pheochromocytoma: report of a rare coexistence

OBJECTIVE

To describe a patient with the rare coexistence of acromegaly and pheochromocytoma.

METHODS

We report a case of a 57-year-old woman, who was initially examined because of polyarthritis, she was also diagnosed with type 2 diabetes mellitus and hypertension at age 56 years. Her history, clinical findings, laboratory results, and management are summarized, and etiologic hypotheses are discussed.

RESULTS

The patient had recurrent headaches and reported an increasing size of her shoes and gloves during the previous 4 years. Enlargement of her hands and feet and a bilateral temporal field defect were noted on examination. Laboratory studies revealed high levels of insulin-like growth factor I (IGF-I) and growth hormone (GH). Magnetic resonance imaging (MRI) showed a 3-cm sellar mass with impingement on the optic chiasm. The plasma level of growth hormone-releasing hormone (GHRH) was normal. She underwent transsphenoidal adenomectomy. Histologic examination confirmed a pituitary adenoma, immunoreactive for GH. Postoperatively, her headaches and arthritic pain diminished, and her levels of IGF-I and GH normalized; however, labile hypertension persisted. The urinary metanephrines and plasma catecholamines were increased. A 3-cm left adrenal mass, seen on abdominal MRI, was removed laparoscopically, after which urinary metanephrines normalized and both the diabetes and the hypertension resolved. Histopathologic analysis confirmed the diagnosis of pheochromocytoma. Immunohistochemical staining was negative for GHRH.

CONCLUSION

The finding of a pheochromocytoma and acromegaly could be a fortuitous coexistence of two separate endocrine tumors; however, the probability of such an event is extremely low. A cause-and-effect relationship has been suggested because of previous reports of GHRH production by pheochromocytomas. Some investigators have also suggested that this coexistence might be a multiple endocrine neoplasia variant. Our patient had no evidence of GHRH production, nor did we document any familial autosomal dominant transmission pattern.

Randomized trial of parathyroidectomy in mild asymptomatic primary hyperparathyroidism: patient description and effects on the SF-36 health survey

BACKGROUND

The treatment of patients with asymptomatic primary hyperparathyroidism remains controversial despite a National Institutes of Health consensus statement. This statement also recommended a randomized clinical trial because none exists to address this issue.

METHODS

Informed consent was obtained from 53 asymptomatic patients with confirmed asymptomatic primary hyperparathyroidism who participated in this randomized trial of parathyroidectomy versus observation. Patients completed the SF-36 Health Survey, an instrument that measures wellness, every 6 months for 2 years. Average annual changes were compared.

RESULTS

Fifty-three patients (42 female, 11 male) with asymptomatic, mild (serum calcium level, 10.1-11.5 mg/dL) asymptomatic primary hyperparathyroidism who agreed to participate were randomized into either a surgical group or an observation group. The mean calcium level was 10.31 mg/dL. The only demographic difference between groups was age, with the operative group being older (66.7 vs 62.6 years; P <.03). The scores on 2 of the 9 domains of the SF-36 were significantly different (P <.007 and <.012, respectively); both favored the operative group.

CONCLUSIONS

Improved function is seen after parathyroidectomy when compared with patients who did not undergo operation. This study supports surgical management of mild primary hyperparathyroidism at the time of diagnosis because many patients have reversible nonclassic symptoms of the disease.

Effect of vitamin D nutrition on parathyroid adenoma weight: pathogenetic and clinical implications

In primary hyperparathyroidism, adenoma size is a major determinant of disease severity and manner of presentation, but the reason for the large variation in size (>100-fold) is unknown. One factor could be the level of vitamin D nutrition, because in India, where vitamin D deficiency is endemic, adenomas are larger and the disease more severe than in the U.S. Accordingly, we determined the relationship between vitamin D nutrition, as measured by serum levels of 25-hydroxyvitamin D (25OHD), and parathyroid gland weight, expressed on a logarithmic scale, in 148 U.S. patients with primary hyperparathyroidism. A significant inverse relationship was found between log gland weight as dependent variable and serum 25OHD as independent variable (r = -0.365; P < 0.0001). The only other influence on gland weight was a weak inverse correlation with age. Log gland weight as an independent variable was significantly related to adjusted calcium, PTH, and alkaline phosphatase (AP) as dependent variables. In 51 patients with serum 25OHD levels less than 15 ng/mL, gland weight, PTH, AP, and adjusted calcium were each significantly higher than in 97 patients with 25OHD levels of 15 ng/mL or more, but 1,25-dihydroxyvitamin D levels were similarly increased in both groups. In the former group the response of adjusted calcium to PTH was blunted, and the response of AP was enhanced, based on significant differences in regression slopes (P = 0.0004 and 0.0022, respectively). Suboptimal vitamin D nutrition stimulates parathyroid adenoma growth by a mechanism unrelated to hypocalcemia or 1,25-dihydroxyvitamin D deficiency and reduces the calcemic response to PTH, so that a higher PTH level and more parathyroid cells are needed to raise the patient's serum calcium to the level corresponding to the increased set-point that is characteristic of the disease. Improved vitamin D nutrition in the population is partly, perhaps largely, responsible for the historical changes in disease severity and manner of presentation that have occurred over the last 50 yr.

Metabolic bone disease in gastrointestinal, hepatobiliary, and pancreatic disorders and total parenteral nutrition

Privational vitamin D deficiency is assumed to be uncommon in the developed countries because of the routine fortification of foods with vitamin D. Malabsorption of vitamin D and calcium (especially in an environment of reduced sun exposure) therefore accounts for the majority of cases of metabolic bone disease seen in patients with various gastrointestinal disorders in the United States. Yet recognition of this often asymptomatic bone disease is unsatisfactory and frequently delayed for months or even years. This results in severe irreversible bone loss, putting patients at increased fracture risk for the remainders of their lives. As evident from the small number of published reports, it is obvious that little attention is given to understanding the pathogenesis and prevention of bone disease in patients with various gastrointestinal disorders. This review will summarize recent advances in the pathogenesis, prevention, and treatment of metabolic bone disease in patients with these disorders. We propose methods for identifying bone loss in such patients so that appropriate preventive measures can be instituted to avoid significant morbidity.