A 75-year-old woman is evaluated in an outpatient clinic for a six-month history of generalized bone pain, particularly prominent in her spine and pelvis. She reports increasing muscle weakness, making it difficult to rise from a chair or climb stairs, and states she has had two low-trauma fractures in the past year: a distal radial fracture from a minor fall and a vertebral compression fracture diagnosed after an episode of severe back pain. Her diet is notable for infrequent consumption of dairy products, and she spends most of her time indoors due to mobility issues. She has a long-standing history of epilepsy treated with carbamazepine. On physical examination, she appears frail with a waddling gait. There is diffuse tenderness on palpation of the tibia and sternum. Proximal muscle strength is diminished (4/5 in upper and lower extremities), and deep tendon reflexes are normal. Vital signs are stable. Given these findings, what is the most likely diagnosis and the appropriate initial therapeutic intervention?

A 3-year-old girl presents to a pediatric outpatient clinic with her parents who report progressive bowing of her lower extremities over the past year. They also note that she seems to be shorter than her peers and complains of generalized bone pain, especially after prolonged activity. Her birth history was uncomplicated, and she has been exclusively breastfed until 1 year of age. Her dietary history is unremarkable, and she has had adequate sun exposure. On examination, her vital signs are stable with a temperature of 36.8°C, blood pressure of 95/60 mm Hg, heart rate of 98 beats/min, respiratory rate of 20 breaths/min, and oxygen saturation of 99% on room air. Physical examination reveals prominent widening of the wrists and ankles, and marked bilateral genu varum (bow-legs). She also exhibits some frontal bossing. Laboratory investigations are initiated to determine the underlying etiology and guide subsequent therapeutic interventions. Considering her clinical presentation and laboratory findings, what is the most likely diagnosis and the cornerstone of her initial medical management?

A 7-year-old girl is brought to a general outpatient clinic by her parents, concerned about recurrent bone fractures. She has experienced five separate fractures, including a tibial shaft fracture, a forearm fracture, and now a recent clavicular fracture, all from what her parents describe as minor falls or everyday activities. Her past medical history is otherwise notable for persistent mild hearing difficulties, for which she uses hearing aids in school. Her biological family history is unknown as she was adopted at an early age. On examination, she is at the 5th percentile for height and 50th percentile for weight. Her sclerae appear distinctly bluish, and there is generalized joint hypermobility, particularly in her elbows and knees. Otoscopic examination reveals normal tympanic membranes, but audiometry confirms a mixed hearing loss. Cardiopulmonary examination is unremarkable. She ambulates independently but with a slightly wide-based gait. A radiograph of the clavicle confirms a non-displaced fracture, and previous imaging reports show well-healed fractures without signs of abnormal mineralization or metaphyseal flaring. The parents are seeking guidance on the underlying cause and appropriate management. Given these findings, what is the most likely diagnosis and the immediate primary treatment consideration?