Relevant genetic variants are common in women with pregnancy and lactation-associated osteoporosis (PLO) and predispose to more severe clinical manifestations

Clinical presentation, risk factors and management of pregnancy-associated osteoporosis: a systematic review and meta-analysis

A systematic review and meta-analysis of the presentation, risk factors and treatment response of pregnancy-associated osteoporosis was conducted involving 35 studies and 943 patients. Vertebral fractures, back pain and family history of osteoporosis were common features. Analysis of treatment response was inconclusive due to limited availability of data.

INTRODUCTION

Pregnancy-associated osteoporosis (PAO) is a rare disorder most often presenting with vertebral fractures during pregnancy or postpartum.

AIMS

This meta-analysis aimed to evaluate the presenting features of PAO, its risk factors and the effectiveness of various treatments at improving bone mineral density (BMD) and preventing further fractures.

METHODS

A systematic search of PubMed, EMBASE and Web of Science identified 35 studies comprising 943 cases of PAO. A meta-analysis was conducted to evaluate the effect of treatment on change in BMD at the lumbar spine, femoral neck and total hip.

RESULTS

Vertebral fractures and back pain occurred in 89.2% and 90.2% of cases, respectively. The diagnosis was predominantly made postpartum. The most common risk factor was a family history of osteoporosis (40.5%). Calcium and vitamin D supplements (31.8%) and teriparatide (30.8%) were the most commonly used treatments. The meta-analysis of BMD response was inconclusive due to limited availability of data. The BMD change at the lumbar spine was greater with teriparatide compared with calcium/vitamin D and bisphosphonates but this was based on only two studies. There was no difference in BMD response at the femoral neck. Recurrent fractures were reported in 12.9% with no difference between treatment groups.

CONCLUSION

While this review can assist clinicians with the diagnosis and management of PAO, it highlights some key knowledge gaps that may inform conduct of a Delphi process on the diagnosis and management of this disorder, pending conduct of randomised controlled trials.

Femoral Fracture in Pregnancy: A Case Report and Review of Data from the Literature

BACKGROUND

Orthopedic trauma during pregnancy is a rare yet complex medical challenge, impacting both maternal and fetal health. Among these, femoral fractures are particularly uncommon but require careful management to minimize maternal and fetal risks.

METHODS

We report the case of a 28-year-old woman, gravida 4, para 3, at 40 weeks of gestation, who sustained a left mid-femoral diaphyseal fracture following a low-energy fall. A multidisciplinary team approach, including obstetric, orthopedic, anesthetic, and neonatal specialists, was employed. Preoperative imaging by X-ray was performed under lead-apron protection. The patient underwent an emergency C-section, followed by closed reduction and internal fixation with an intramedullary nail.

RESULTS

The surgical intervention was successful, with minimal radiation exposure. Postoperative management included thromboprophylaxis, calcium, vitamin D supplementation, and physiotherapy. The patient recovered well, achieving fracture healing within three months. Postpartum bone density assessment was recommended, suspecting pregnancy- and lactation-associated osteoporosis.

CONCLUSIONS

Managing femoral fractures during pregnancy necessitates a balance between maternal and fetal well-being. A collaborative, multidisciplinary approach ensures optimal outcomes. Early surgical intervention, proper radiation precautions, and postpartum bone health assessment are crucial in these cases. Further research is needed to understand risk factors and preventive strategies for pregnancy-associated osteoporosis.

[Pregnancy and lactation-associated osteoporosis: risk factors and treatment]

Pregnancy and lactation-associated osteoporosis (PLO) is a rare but serious condition. Multiple fractures often occur, mostly in the form of vertebral fractures, the mother is severely restricted and caring for the infant is barely possible without assistance. The fractures causing the complaints usually occur in the last trimester of the first pregnancy or in the first weeks of lactation. Magnetic resonance imaging (MRI) can be used to detect vertebral fractures and also edematous vertebrae. Bone densitometry is helpful for the diagnostics and assessment of progression. It is extremely important to distinguish PLO from other secondary forms of osteoporosis that can also be manifested during pregnancy and lactation. The mother is advised to stop breastfeeding immediately in order to interrupt calcium mobilization from bone and to achieve a normalization of hormone levels. Calcium and vitamin D should be supplemented and adequate pain treatment and physiotherapy should be initiated. The quality of data is poor due to the rarity of the disease, all available anti-osteoporotic drugs have been used in case reports but overall, in the last decade off-label treatment with teriparatide has been proven to be helpful and safe.

HR-pQCT reveals marked trabecular and cortical structural deficits in women with pregnancy and lactation-associated osteoporosis (PLO)

Pregnancy and lactation-associated osteoporosis (PLO) is a rare presentation of early-onset osteoporosis characterized by low trauma and spontaneous fractures during late pregnancy/lactation. Herein, we report areal BMD (aBMD) by DXA and volumetric BMD (vBMD), microarchitecture, and strength at the distal radius and tibia by HR-pQCT in 59 women with PLO-in comparison to both healthy premenopausal controls (n = 28) and premenopausal women with idiopathic osteoporotic fractures not associated with pregnancy/lactation (non-PLO IOP; n = 50). Women with PLO (aged 34 ± 6 yr) had a more severe clinical presentation than non-PLO IOP: 80% had vertebral and 92% had multiple fractures (p<.001). They had lower DXA aBMD at all sites vs Controls (all p<.001) and non-PLO IOP (all p<.05). By HR-pQCT, PLO had deficits in all radial/tibial density and most microarchitecture parameters and lower bone strength than controls (all p<.001). Compared to non-PLO IOP, PLO had lower total and trabecular density at radius and tibia (all p ≤ .01) and significant deficits in trabecular microstructure and cortical thickness at the radius only. We studied PLO subgroups with clinical factors potentially related to bone physiology: Within PLO, women with vertebral fractures had lower spine aBMD and higher tibial cortical porosity but were otherwise structurally similar to the nonvertebral group. Those with prior heparin exposure had larger bone size and trabecular area, and those with renal stones had smaller bone size and lower 1/3 radius aBMD. We also compared groups based on postpartum timing: Recent PLO (n = 25) evaluated ≤12 M postpartum, before expected recovery of pregnancy/lactation bone loss, had significantly lower aBMD than distant PLO (n = 34) evaluated >12 M postpartum. However, radial/tibial HR-pQCT measures did not differ, suggesting pre-existing and/or persistent structural deficits. This structural study increases our mechanistic understanding of the severe bone fragility presentation that characterizes PLO and also highlights areas of potential mechanistic heterogeneity that require additional investigation.

Current and future perspectives on pregnancy and lactation-associated osteoporosis

Normal pregnancy and lactation have a marked physiological impact on maternal bone metabolism. This impact is usually temporary and reversible, but some women sustain fragility fractures whilst pregnant or lactating, termed pregnancy and lactation-associated osteoporosis (PLO). These fractures have severe negative consequences on their quality of life, at what is a crucial stage in a mother's life. Identifiable risk factors include a low body mass index (BMI), reduced physical activity during adolescence, a strong family history of osteoporosis, and genetic variations in the LRP5 and WNT1 genes. However, due to the rarity of PLO and the limited awareness surrounding it, there has been slow progress in understanding its pathophysiology and identifying the most effective treatments. Indeed, the data available primarily originates from observational and case studies, resulting in little clear guidance on a comprehensive and multidisciplinary approach. This mini-review synthesises the latest data on incidence, pathophysiology, and management in PLO, providing current and future perspectives and highlights the need for evidence-based guidelines to improve both short-term and long-term outcomes for women with PLO.

Effective strategies for pregnancy and lactation-associated osteoporosis: teriparatide use in focus

INTRODUCTION

Pregnancy and lactation-associated osteoporosis (PLO) is a rare condition characterized by fragility fractures occurring during late pregnancy or lactation, primarily affecting the spine and causing significant morbidity and back pain. PLO can lead to mobility impairment and work incapacity, with recovery taking up to several years. Due to the lack of clinical trials, treatment strategies remain poorly defined, historically focusing on calcium supplements, vitamin D, and weaning from breastfeeding. However, recent attention has turned to teriparatide (TPD) as an option due to its anabolic properties and potential suitability for women of childbearing age.

METHODS

This review evaluates TPD's use in PLO treatment, using published systematic reviews and case studies. Over 300 cases with PLO were identified through PubMed, Google Scholar, and Cochrane searches until August 2023.

RESULTS

We identified 175 cases with PLO treated with TPD alone or followed by antiresorptive therapy. Most women (85.7%) were primiparas. The mean ± SD duration of TPD use was 15 ± 6 months. Among the study patients, 91.4% used TPD alone, while 8.6% (15/175) utilized sequential therapy. Approximately 93% of our cohort exhibited potential risk factors for PLO. Despite the increased risk of recurrent fractures in PLO, only 14.7% (20/175) of those treated with TPD sustained new fractures during a 9-month to 9 years' follow-up period. The mean ± SD percent increase in BMD at the LS was 21.14% ± 7.4%, and at the FN it was 12.1% ± 9.3%. The baseline Z-scores at the LS ranged from -3.3 (-3.7 to -2.7), while the baseline Z-scores at the FN ranged from -2.0 (-2.7 to -1.5).

CONCLUSION

This review emphasizes PLO severity, advocating for increased awareness and timely interventions. TPD emerges as a promising therapeutic option in certain cases.

Prevalence Characteristics of Osteoporosis Fractures in the Elderly in Two Regions of China and Analysis of the Lag Effect of Air Pollutants on them

OBJECTIVE

Air pollution is increasing and threatening human health. The objective of this study is to investigate the population distribution characteristics of elderly osteoporosis fractures in Hebei Province and Xinjiang Uygur Autonomous Region and to analyze the effects of air pollutants on the number of elderly osteoporosis fracture inpatients in the two regions.

METHOD

A retrospective collection of elderly osteoporosis fracture cases was conducted in selected hospitals in Hebei Province and Xinjiang Uygur Autonomous Region from January 1, 2018 to December 31, 2022. The chi-square test was used to compare the distributional characteristics of the population in the two regions. Additionally, we used a distributed lag nonlinear model (DLNM) in order to assess the effect of air pollutants on the number of daily hospital admissions of elderly osteoporosis fracture patients in different regions.

RESULT

A total of 19,203 elderly osteoporosis fracture patients were included in the study. The average age of these patients was 76.66 ± 7.55 years, and the majority of them were female (13,514 instances, 70.37%). The disparities in age distribution (χ2 = 133.9 p < 0.001), fracture site (χ2 = 62.0 p < 0.001), and hospitalization cost (Z = -15.635 p < 0.001) between the two regions were statistically significant. The lag effect curves of PM2.5, PM10, and NO2 on the number of elderly osteoporosis fracture hospitalizations in Xinjiang Uygur Autonomous Region exhibited a similar pattern resembling a "W"-shaped curve. All three pollutants reached their highest values after a lag time of 14 days (PM2.5: RR = 1.053, 95% CI: 1.031, 1.074; PM10: RR = 1.031, 95% CI: 1.018, 1.043; NO2: RR = 1.125, 95% CI: 1.070, 1.182). In Hebei Province, the largest impacts of PM2.5 and PM10 were observed after a lag of 14 days (PM2.5: RR = 1.022, 95% CI: 1.013, 1.028; PM10: RR = 1.013, 95% CI: 1.008, 1.018). Similarly, the maximum effect of NO2 was observed after a lag of 11 days (RR = 1.020, 95% CI: 1.010, 1.028).

CONCLUSION

There were differences in the epidemiological characteristics of hospitalized patients with osteoporosis fractures between the two regions, PM2.5, PM10, and NO2 increased the number of hospitalizations for osteoporosis fractures. Exposure to air pollutants such as PM2.5 increases the risk of osteoporosis fractures in the elderly population.

Bone Metabolism, Bone Mass, and Bone Structure During Pregnancy and Lactation: Normal Physiology and Pregnancy and Lactation-Associated Osteoporosis

This article reviews bone metabolism, bone mass, and bone structure changes expected during and after pregnancy and lactation, as well as the condition of pregnancy and lactation-associated osteoporosis (PLO)-a presentation with fragility fracture(s) in the context of these physiologic changes. Clinical implications of physiologic bone changes will be addressed, as will specific management considerations that apply to premenopausal women with PLO.

Comparative Effectiveness of Therapeutic Interventions in Pregnancy and Lactation-Associated Osteoporosis: A Systematic Review and Meta-analysis

CONTEXT

The optimal management of pregnancy and lactation-associated osteoporosis (PLO) has not been designated.

OBJECTIVE

To systematically review the best available evidence regarding the effect of different therapeutic interventions on bone mineral density (BMD) and risk of fractures in these patients.

METHODS

A comprehensive search was conducted in PubMed/Scopus databases until December 20, 2022. Data were expressed as weighted mean difference (WMD) with 95% CI. The I2 index was employed for heterogeneity. Studies conducted in women with PLO who received any antiosteoporosis therapy were included. Studies including women with secondary causes of osteoporosis or with transient osteoporosis of the hip were excluded. Data extraction was independently completed by 2 researchers.

RESULTS

Sixty-six studies were included in the qualitative analysis (n = 451 [follow-up time range 6-264 months; age range 19-42 years]). The increase in lumbar spine (LS) BMD with calcium/vitamin D (CaD), bisphosphonates, and teriparatide was 2.0% to 7.5%, 5.0% to 41.5%, and 8.0% to 24.4% at 12 months, and 11.0% to 12.2%, 10.2% to 171.9%, and 24.1% to 32.9% at 24 months, respectively. Femoral neck (FN) BMD increased by 6.1% with CaD, and by 0.7% to 18% and 8.4% to 18.6% with bisphosphonates and teriparatide (18-24 months), respectively. Meta-analysis was performed for 2 interventional studies only. Teriparatide induced a greater increase in LS and FN BMD than CaD (WMD 11.5%, 95% CI 4.9-18.0%, I2 50.9%, and 5.4%, 95% CI 1.2-9.6%, I2 8.1%, respectively).

CONCLUSION

Due to high heterogeneity and lack of robust comparative data, no safe conclusions can be made regarding the optimal therapeutic intervention in women with PLO.

Long-term and sequential treatment for osteoporosis

Osteoporosis is a skeletal disorder that causes impairment of bone structure and strength, leading to a progressively increased risk of fragility fractures. The global prevalence of osteoporosis is increasing in the ageing population. Owing to the chronic character of osteoporosis, years or even decades of preventive measures or therapy are required. The long-term use of bone-specific pharmacological treatment options, including antiresorptive and/or osteoanabolic approaches, has raised concerns around adverse effects or potential rebound phenomena after treatment discontinuation. Imaging options, risk scores and the assessment of bone turnover during initiation and monitoring of such therapies could help to inform individualized treatment strategies. Combination therapies are currently used less often than 'sequential' treatments. However, all patients with osteoporosis, including those with secondary and rare causes of osteoporosis, as well as specific patient populations (for example, young adults, men and pregnant women) require new approaches for long-term therapy and disease monitoring. New pathophysiological aspects of bone metabolism might therefore help to inform and revolutionize the diagnosis and treatment of osteoporosis.

Recent Insights into Pregnancy and Lactation-Associated Osteoporosis (PLO)

During pregnancy and lactation, female physiology adapts to fulfill the fetal and neonatal calcium and phosphorus requirements. The physiological changes that take place during these periods do not affect maternal skeleton resistance to fracture in most of the cases. However, there is a small percentage of women that do experience fragility fractures during these times of life. Pregnancy and lactation-associated osteoporosis (PLO) is an infrequent condition defined by the occurrence of non-traumatic fractures - most frequently vertebral - during the third trimester of gestation and/or the first months of postpartum. Its physiopathology has not yet been completely elucidated. Several authors have reported that risk factors for secondary osteoporosis might be present in up to 80% of the cases of PLO patients. According to recent studies, genetic factors might also play a relevant role in PLO. Given its rarity, the available literature on this condition is limited. Most of the published data consist on case reports and case series articles. There are not any randomized controlled trials regarding this disorder. Although there is consensus about discontinuation of lactation and calcium and vitamin D supplementation as the first steps in the treatment of these patients, there is still controversy regarding the long-term and/or pharmacological management of this condition. Recent data on the use of teriparatide in this population looks promising. In this review, we aimed to revise and summarize current knowledge about the physiopathology and management of PLO.

Dynamics of Skeletal Status under Optimized Management during Subsequent Pregnancy in Three Women with a History of Pregnancy- and Lactation-Associated Osteoporosis Carrying pathogenic Variants in WNT1 and LRP5

Pregnancy- and lactation-associated osteoporosis (PLO) is a rare but clinically highly relevant condition, characterized by reduced bone mineral density (BMD) and acute onset of severe pain due to symptomatic bone marrow edema of the hip or vertebral and/or insufficiency fractures, among others. Previous reports showed a high frequency of hereditary bone disorders unmasked by PLO, predisposing for more severe forms. To date, no data on the risk for additional fractures during subsequent pregnancy in women with PLO and genetic bone disorder have been available. To address this question, we retrospectively analyzed the clinical, biochemical, and densitometric course of three women with a history of PLO and detected variants in WNT1 or LRP5 and subsequent pregnancies. Calcium homeostasis and bone turnover were optimized by basic treatment, and timely initiation of weaning was recommended. Teriparatide treatment for 12 months under strict contraception was initiated in one woman after the diagnosis of PLO. In none of the women did additional fractures or symptomatic bone marrow edemas occur, and BMD by dual-energy X-ray absorptiometry as bone microarchitecture by high-resolution peripheral quantitative computed tomography remained stable. In conclusion, this report expands the understanding of this rare but severe condition and helps to improve clinical counseling and management. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Pregnancy and lactation-associated osteoporosis with pyogenic spondylitis: A case report

BACKGROUND

This case report presents a patient with pyogenic spondylitis (PS) associated with lactation-related osteoporosis during pregnancy. The 34-year-old female patient experienced low back pain for one month, beginning one month postpartum, with no history of trauma or fever. Dual-energy X-ray absorptiometry of the lumbar spine revealed a Z-score of -2.45, leading to a diagnosis of pregnancy and lactation-associated osteoporosis (PLO). The patient was advised to cease breastfeeding and take oral calcium and active vitamin D. Despite these interventions, her symptoms worsened, and she had difficulty walking one week later, prompting her to revisit our hospital.

CASE SUMMARY

Lumbar magnetic resonance imaging (MRI) scans showed abnormal signals in the L4 and L5 vertebral bodies and intervertebral space, while an enhancement scan displayed abnormal enhanced high signals around the L4/5 intervertebral disc, suggesting a lumbar infection. A needle biopsy was performed for bacterial culture and pathological examination, culminating in a final diagnosis of pregnancy and lactation-related osteoporosis with PS. Following treatment with anti-osteoporotic medications and antibiotics, the patient’s pain gradually subsided, and she returned to normal life within five months. PLO is a rare condition that has garnered increasing attention in recent years. Spinal infections during lactation in pregnancy are also relatively uncommon.

CONCLUSION

Both conditions primarily manifest as low back pain but require distinct treatments. In clinical practice, when diagnosing patients with pregnancy and lactation-associated osteoporosis, the possibility of spinal infection should be considered. A lumbar MRI should be conducted as needed to prevent delays in diagnosis and treatment.

Bridging the Gap: Pregnancy-And Lactation-Associated Osteoporosis

Early diagnosis of pregnancy- and lactation-associated osteoporosis (PLO) is mandatory for a good outcome. Standard care is not a matter of conventional guidelines, rather it requires an individualized strategy while true overall incidence and pathogeny remain open issues. This is a narrative review based on full-length English articles, published between January 2021 and March 2023 and accessed via PubMed (no traumatic fractures or secondary osteoporosis are included). Our case-sample-based analysis included 836 females with PLO (the largest cohort based on published cases so far) through 12 studies and 24 single case reports. Except for one survey, these involved retrospective cohorts of small size (6-10 females/study) to medium size (23-47 women/study), and large cohorts with >50 subjects per study (a maximum of 379). Age of diagnosis: from 24 to 40 years for case reports (most subjects being over 30 and primigravida), while original studies indicated an average age between 31 and 34.18 years. Type of fractures underlined a most frequent vertebral phenotype (a mean of 2 to 5.8 vertebral fractures per patient) versus a most severe non-vertebral phenotype (hip and femoral neck fractures mostly requiring surgery). Potential contributors varied: smoking (1/3-1/2 of subjects), family history of osteoporosis (1/3), heparin and glucocorticoid use in pregnancy, low body mass index (majority of cases), hypovitaminosis D; and (with a low level of statistical significance) anti-psychotic medication, gestational diabetes, lupus, thrombophilia, anemia, in vitro fertilization (1/3 in one study), twin pregnancy, tocolysis with MgSO4, and postpartum thyroiditis. Most remarkably, up to 50% of PLO patients harbor mutations of LRP5, WNT1, and COL1A1/A2 (more damaged form with potential benefits from osteoanabolic drugs); gene testing might become the new norm in PLO. The low index of clinical suspicion should be supported by performing magnetic resonance imaging (gold standard in pregnancy) with DXA (in lactation). Low bone mineral density is expected (Z-score varying from -2.2 SD to -4 SD, unless normal which does not exclude PLO). Bone turnover markers might be useful in individuals with normal DXA, in pregnancy when DXA cannot be performed, and in following the response to anti-osteoporosis drugs. Alternatively, microarchitecture damage might be reflected by DXA-trabecular bone score and high-resolution peripheral quantitative computed tomography. Specific medical interventions are currently focused on teriparatide (TPT) use (3 studies; n = 99 females treated with TPT and an additional subgroup of 18 patients from the gene-analysis-based study, thus a total of 117 females) which seems to be the therapy of choice as reflected by these new data: 6-24 months, 20 µg/day, no sequential therapy needed; case selection based on high fracture risk is necessary). The first case using romosozumab was reported in 2022. PAO/LAO remains a challenging condition which is a battle for the wellbeing of two individuals, on one hand, considering maternal-fetal outcomes and taking care of the offspring, but it is a battle for a multidisciplinary team, on the other hand, since a standardized approach is lacking.

Pregnancy- and lactation-induced osteoporosis: a social-media-based survey

BACKGROUND

Pregnancy- and lactation-induced osteoporosis (PLO) presenting as spinal fractures is rare, and the spectrum of clinical presentation, risk factors and pathophysiology are incompletely understood. The aim of this study was to delineate clinical parameters, risk factors and osteoporosis-related quality of life (QOL) of women with PLO.

METHODS

Participants of a social-media (WhatsApp) PLO group and mothers of a parents' WhatsApp group (control group) were offered to fill a questionnaire, including an osteoporosis-related QOL section. The groups were compared using the independent Students t test for numerical variables, and the Chi-square test or Fisher's exact test for categorical variables.

RESULTS

Twenty-seven women with PLO and 43 in the control group (aged 36.2 ± 4.7 and 38.8 ± 4.3 years, respectively, p = 0.04) participated. Among women with PLO, more than 5 vertebrae were involved in 13 (48%), 4 vertebrae in 6 (22%), and 3 or fewer vertebrae in 8 (30%). Among the 24 women with relevant data, 21 (88%) had nontraumatic fractures; 3 (13%) women had fractures during pregnancy, and the remaining during the early postpartum period. Diagnosis was delayed for over 16 weeks for 11 (41%) women; 16 (67%) received teriparatide. Significantly lower proportions of women in the PLO group engaged in physical activity over 2 hours/week, before and during pregnancy (37 vs. 67%, p < 0.015 and 11 vs. 44%, p < 0.003, respectively). A lower proportion of the PLO than the control group reported calcium supplementation during pregnancy (7% vs. 30%, p = 0.03) and a higher proportion reported treatment with low-molecular-weight-heparin during pregnancy (p = 0.03). Eighteen (67%) of the PLO group expressed fear of fractures and 15 (56%) fear of falls, compared to none and 2%, respectively, of the control group (p < 0.00001 for both).

CONCLUSIONS

Most of the women with PLO who responded to our survey reported spinal fractures involving multiple vertebrae, delayed diagnosis, and treatment with teriparatide. Compared to a control group, they reported less physical activity and impaired QOL. For this uncommon yet severe condition, a multidisciplinary effort should be exerted for early identification and treatment, to alleviate back pain, prevent subsequent fractures and improve QOL.

Bone Microarchitecture and Strength Changes During Teriparatide and Zoledronic Acid Treatment in a Patient with Pregnancy and Lactation-Associated Osteoporosis with Multiple Vertebral Fractures

Pregnancy- and lactation-associated osteoporosis (PLO) is a rare form of osteoporosis, of which the pathogenesis and best treatment options are unclear. In this report, we describe the case of a 34-year old woman diagnosed with severe osteoporosis and multiple vertebral fractures after her first pregnancy, who was subsequently treated with teriparatide (TPTD) and zoledronic acid (ZA). We describe the clinical features, imaging examination, and genetic analysis. Substantial improvements were observed in areal and volumetric bone mineral density (BMD), microarchitecture, and strength between 7 and 40 months postpartum as assessed by dual-energy X-ray absorptiometry at the total hip and spine and by high-resolution peripheral quantitative CT at the distal radius and tibiae. At the hip, spine, and distal radius, these improvements were mainly enabled by treatment with TPTD and ZA, while at the distal tibiae, physiological recovery and postpartum physiotherapy due to leg pain after stumbling may have played a major role. Additionally, the findings show that, despite the improvements, BMD, microarchitecture, and strength remained severely impaired in comparison with healthy age- and gender-matched controls at 40 months postpartum. Genetic analysis showed no monogenic cause for osteoporosis, and it is suggested that PLO in this woman could have a polygenic origin with possible susceptibility based on familiar occurrence of osteoporosis.

Clinical Spectrum of Hereditary Hypophosphatemic Rickets With Hypercalciuria (HHRH)

Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) represents an FGF23-independent disease caused by biallelic variants in the solute carrier family 34-member 3 (SLC34A3) gene. HHRH is characterized by chronic hypophosphatemia and an increased risk for nephrocalcinosis and rickets/osteomalacia, muscular weakness, and secondary limb deformity. Biochemical changes, but no relevant skeletal changes, have been reported for heterozygous SLC34A3 carriers. Therefore, we assessed the characteristics of individuals with biallelic and monoallelic SLC34A3 variants. In 8 index patients and 5 family members, genetic analysis was performed using a custom gene panel. The skeletal assessment comprised biochemical parameters, areal bone mineral density (aBMD), and bone microarchitecture. Pathogenic SLC34A3 variants were revealed in 7 of 13 individuals (2 homozygous, 5 heterozygous), whereas 3 of 13 carried monoallelic variants of unknown significance. Whereas both homozygous individuals had nephrocalcinosis, only one displayed a skeletal phenotype consistent with HHRH. Reduced to low-normal phosphate levels, decreased tubular reabsorption of phosphate (TRP), and high-normal to elevated values of 1,25-OH₂ -D₃ accompanied by normal cFGF23 levels were revealed independently of mutational status. Interestingly, individuals with nephrocalcinosis showed significantly increased calcium excretion and 1,25-OH₂ -D₃ levels but normal phosphate reabsorption. Furthermore, aBMD Z-score <-2.0 was revealed in 4 of 8 heterozygous carriers, and HR-pQCT analysis showed a moderate decrease in structural parameters. Our findings highlight the clinical relevance also of monoallelic SLC34A3 variants, including their potential skeletal impairment. Calcium excretion and 1,25-OH₂ -D₃ levels, but not TRP, were associated with nephrocalcinosis. Future studies should investigate the effects of distinct SLC34A3 variants and optimize treatment and monitoring regimens to prevent nephrocalcinosis and skeletal deterioration. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Effect of Teriparatide on Subsequent Fracture and Bone Mineral Density in 47 Women with Pregnancy- and Lactation-associated Osteoporosis and Vertebral Fractures

Introduction Pregnancy- and lactation-associated osteoporosis (PLO) with predominantly vertebral fractures is a rare but severe disease which can occur in the last trimester of pregnancy or postpartum. The aim of the present study was to assess the impact of teriparatide on subsequent fractures and bone mineral density (BMD) in patients with PLO.

Materials and Methods A total of 47 patients with PLO and postpartum spinal fractures (mean: 4 fractures) undergoing treatment with teriparatide were investigated. The data collection period was set between 2006 and 2018. All patients received a subcutaneous injection of 20 µg teriparatide once a day for 24 months as well as individually adapted vitamin D supplementation. After 24 months of treatment, all women received no further treatment and either had regular menstrual cycles or took oral contraceptives. Fractures were confirmed by X-ray or MRI. Changes in BMD from baseline were examined using serial DXA measurements.

Results After 24 months of teriparatide treatment, we could demonstrate an increase in BMD at the lumbar spine, femoral neck and total hip of + 30.1%, + 11.7% and + 12.2% respectively (p < 0.001 for all). At 12 months after cessation of treatment, BMD remained stable compared to the 24-month measurements at the lumbar spine, femoral neck and total hip which showed non-significant changes of + 1.4%, + 2.6% and + 4.1% respectively. Out of the 47 patients with PLO with a mean of 4 existing fractures, 4 patients (7.8%) sustained a subsequent fracture, two after 3 – 5 months of treatment and two at > 6 months of treatment.

Conclusion 24 months of treatment with teriparatide in women with PLO and multiple vertebral fractures significantly increased BMD, predominantly BMD of the spine. As patients were premenopausal, there was no significant decrease in BMD in the following 12 months after cessation of treatment.

Whole exome sequencing reveals potentially pathogenic variants in a small subset of premenopausal women with idiopathic osteoporosis

Osteoporosis in premenopausal women with intact gonadal function and no known secondary cause of bone loss is termed idiopathic osteoporosis (IOP). Women with IOP diagnosed in adulthood have profound bone structural deficits and often report adult and childhood fractures, and family history of osteoporosis. Some have very low bone formation rates (BFR/BS) suggesting osteoblast dysfunction. These features led us to investigate potential genetic etiologies of bone fragility. In 75 IOP women (aged 20-49) with low trauma fractures and/or very low BMD who had undergone transiliac bone biopsies, we performed Whole Exome Sequencing (WES) using our variant analysis pipeline to select candidate rare and novel variants likely to affect known disease genes. We ran rare-variant burden analyses on all genes individually and on phenotypically-relevant gene sets. For particular genes implicated in osteoporosis, we also assessed the frequency of all (including common) variants in subjects versus 6540 non-comorbid female controls. The variant analysis pipeline identified 4 women with 4 heterozygous variants in LRP5 and PLS3 that were considered to contribute to osteoporosis. All 4 women had adult fractures, and 3 women also had multiple fractures, childhood fractures and a family history of osteoporosis. Two women presented during pregnancy/lactation. In an additional 4 subjects, 4 different relevant Variants of Uncertain Significance (VUS) were detected in the genes FKBP10, SLC34A3, and HGD. Of the subjects with VUS, 2 had multiple adult fractures, childhood fractures, and presented during pregnancy/lactation, and 2 had nephrolithiasis. BFR/BS varied among the 8 subjects with identified variants; BFR/BS was quite low in those with variants that are likely to have adverse effects on bone formation. The analysis pipeline did not discover candidate variants in COL1A1, COL1A2, WNT, or ALPL. Although we found several novel and rare variants in LRP5, cases did not have an increased burden of common LRP5 variants compared to controls. Cohort-wide collapsing analysis did not reveal any novel disease genes with genome-wide significance for qualifying variants between controls and our 75 cases. In summary, WES revealed likely pathogenic variants or relevant VUS in 8 (11%) of 75 women with IOP. Notably, the genetic variants identified were consistent with the affected women's diagnostic evaluations that revealed histological evidence of low BFR/BS or biochemical evidence of increased bone resorption and urinary calcium excretion. These results, and the fact that the majority of the women had no identifiable genetic etiology, also suggest that the pathogenesis of and mechanisms leading to osteoporosis in this cohort are heterogeneous. Future research is necessary to identify both new genetic and non-genetic etiologies of early-onset osteoporosis.

A novel mutation in collagen gene COL1A2 associated with transient regional osteoporosis

A young man was diagnosed with transient regional osteoporosis (TRO). The genetic analysis revealed a novel de novo likely pathogenic variant in COL1A2 gene. Our hypothesis is that TRO may be a possible clinical manifestation of osteogenesis imperfecta due to a reduced bone mass and an impaired trabecular mechanical competence.

INTRODUCTION

Transient regional osteoporosis (TRO) is a disease characterized by episodes of pain in the lower limbs involving the hip, knee, ankle or foot. Here, we present a clinical case of a Caucasian 25-year-old man exhibiting TRO. Based on few mild clinical findings suggestive of osteogenesis imperfecta (OI), but without a history of fragility fractures, we performed a genetic assessment to investigate this hypothesis.

METHODS

Medical history was obtained from the patient and family members, including biochemical, RMI and DXA assessments. Next-generation sequencing of COL1A1, COL1A2, COL2A1, CASR, CYP19A1, CUL7, CRTAP, KAL1, LEPRE1, LRP5, PPIB and SLC9A3R1, genes involved in juvenile osteoporosis, was performed.

RESULTS

We identified a novel de novo heterozygous missense variant, c.488G > A, in exon 11 of the COL1A2 gene (NM_000089.3), resulting in the putative p.Gly163Asp substitution in the N-terminal part of the helical domain of type I collagen. The variant was predicted to be damaging by the in silico prediction tools and the mutation was therefore classified as likely pathogenic. This mutation can affect skeletal health impairing bone mass and trabecular mechanical competence, inducing a disease whose features strictly evoke a TRO.

CONCLUSION

The present study describes a novel de novo heterozygous missense variant in COL1A2 gene, possibly inducing a propensity to trabecular microfractures. The recurrent symptomatic bone marrow oedema episodes could be the clinical picture consistent with the hypothesis of an inherited connective tissue disorder giving bone fragility.

Teriparatide Treatment in Patients with Pregnancy- and Lactation-Associated Osteoporosis

Pregnancy- and lactation-associated osteoporosis (PLO) is a rare disease, presenting in most cases with severe back pain due to low energy vertebral fractures (VFs). Our purpose was to assess the effect of teriparatide (TPTD) vs. conventional management on areal bone mineral density (aBMD) and trabecular bone score (TBS) in patients with PLO. A multicenter retrospective cohort study concerning premenopausal women with PLO. Nineteen women were treated with TPTD (20 μg/day) (group A) plus calcium and vitamin D and eight women with calcium and vitamin D only (group B) for up to 24 months. The primary end-point was between group differences in lumbar spine (LS) and total hip (TH) aBMD, and TBS at 12 and 24 months. Patients in group A had sustained a median of 4.0 VFs (3-9) vs. 2.5 VFs (1-10) in group B (p = 0.02). At 12 months, patients on TPTD vs. controls achieved a mean aBMD increase of 20.9  ±  11.9% vs. 6.2  ±  4.8% at the LS (p < 0.001), 10.0  ±  11.6% vs. 5.8  ±  2.8% at the TH (p = 0.43), and 6.7  ±  6.9% vs. 0.9  ±  3.7% in TBS (p = 0.09), respectively. At 24 months, seven patients on TPTD and six controls achieved a mean LS aBMD increase of 32.9  ±  13.4% vs. 12.2  ±  4.2% (p = 0.001). P1NP levels during the first month of TPTD treatment were positively correlated with the 1-year LS aBMD change (r = 0.68, p = 0.03). No new clinical fractures occurred while on-treatment. In patients with PLO, TPTD treatment resulted in significantly greater increases in LS aBMD compared with calcium and vitamin D supplementation at 12 and 24 months.