Vitamin D testing is commonly performed in adults. Evidence is lacking to support vitamin D screening or supplementation in the general population, regardless of baseline serum 25-hydroxyvitamin D levels. The National Academy of Medicine recommends that individuals 70 years and younger consume 600 IU of vitamin D daily and that individuals older than 70 years consume 800 IU daily. This can be achieved through dietary sources, supplements, or both. Achieving the recommended intake prevents serum 25-hydroxyvitamin D levels from decreasing to less than 12 ng/mL in 97.5% of the general population. Randomized controlled trials of vitamin D supplementation in the general population, including patients with low baseline serum 25-hydroxyvitamin D levels, do not demonstrate reduced all-cause mortality or improvement in cardiovascular health. Some patients with prediabetes may benefit from taking at least 3 years of vitamin D supplementation that exceeds the recommended dietary intake to reduce the risk of progression to type 2 diabetes. Randomized controlled trials of vitamin D supplementation for reducing the risk of falls and fractures, cancer, dementia, respiratory infections, and depression; for symptoms of fatigue, hair loss, and chronic pain; and during pregnancy and menopause do not show consistent benefit, including in patients with low baseline serum 25-hydroxyvitamin D levels.

Family physicians are uniquely positioned to provide comprehensive care of patients across the cancer care continuum. Their longitudinal relationship with patients allows them to address cancer-related issues in addition to chronic disease management, preventive care, psychosocial needs, and caregiver support. Maintaining awareness of a patient's cancer diagnosis and related treatment is essential for evaluating new symptoms, recognizing treatment-related adverse effects, and identifying potential oncologic emergencies. Cancer treatment often complicates management of existing chronic illnesses, requiring close monitoring, medication adjustments, and attention to lifestyle factors and nutritional status. Goals of diabetes management include optimal glycemic control to prevent delays in oncologic surgeries, impaired wound healing, and difficulty in managing chemotherapy. Screening for cardiovascular disease should be performed for patients with cancer and known cardiac risk factors or oncologic treatment exposures known to cause cardiac complications. Consistent physical activity is recommended during cancer treatment to improve quality of life. Family physicians frequently serve as the first point of contact when patients experience adverse effects or complications from cancer therapies, many of which can affect physical function, mental health, and quality of life. Effective coordination between oncologists and family physicians is essential to ensure patients receive holistic, person-centered care.

Childhood skin rashes are frequently evaluated by primary care physicians and are often diagnosed by recognition of distinguishing features. Atopic dermatitis affects 15% to 20% of children, usually with onset before the age of 2 years. Treatment is based on severity and begins with emollients and topical steroids. Erythema infectiosum presents with the slapped cheek rash that progresses to reticular lesions on the trunk and extremities. Hand-foot-and-mouth disease presents with painful oral ulcers and vesicular eruption of the hands, feet, buttocks, and genitals. Nonbullous impetigo is characterized by lesions with honey-colored crusting, whereas bullous impetigo presents with flaccid bullae; both are treated with antibiotics. Molluscum contagiosum is characterized by dome-shaped umbilicated papules that spontaneously resolve over months to years without intervention but may be treated with cryotherapy, curettage, or topical agents. Pityriasis rosea usually presents with a large herald patch on the trunk followed by the eruption of numerous smaller lesions aligned with Langer lines. Scarlet fever is a group A beta-hemolytic streptococcal infection with a sandpaper-like rash and should be treated with antibiotics to prevent rheumatic fever. Tinea capitis requires treatment with systemic antifungals, whereas tinea corporis is usually treatable with topical agents.