Symptoms

• Fracture after a minor fall or injury, such as a wrist, rib, hip, or vertebral fracture
• Sudden or persistent mid-back/low-back pain, sometimes from a vertebral compression fracture
• Loss of height or a stooped posture over time
• Repeated stress fractures, especially in athletes
• In some people, no pain or signs despite low bone density

Causes in young adults

• Low sex hormones: absent/irregular periods, early menopause, low testosterone, eating disorders, excessive exercise with inadequate nutrition
• Nutritional problems: low calcium/vitamin D intake, being underweight, malabsorption, coeliac disease
• Hormonal disorders: overactive thyroid, overactive parathyroid, Cushing syndrome
• Medicines: long-term steroid tablets such as prednisolone, some anti-seizure medicines, aromatase inhibitors, some cancer treatments, prolonged heparin
• Chronic illness: inflammatory bowel disease, rheumatoid/inflammatory disease, kidney or liver disease, diabetes, some blood disorders
• Smoking, heavy alcohol intake, prolonged immobility
• Rarely, idiopathic osteoporosis, where no cause is found

Diagnosis

• DXA bone-density scan
  • In premenopausal women and men under 50, the Z-score is generally more useful than the T-score.
  • A Z-score of -2.0 or lower means bone density is below the expected range for age, but it does not alone establish osteoporosis.
• Assessment for fragility fractures, including possible vertebral imaging
• Blood tests such as calcium, phosphate, alkaline phosphatase, vitamin D, kidney/liver function, thyroid-stimulating hormone, parathyroid hormone, full blood count, and hormone tests when appropriate
• Tests directed by the history, for example coeliac screening or evaluation for cortisol excess

Treatment

1. Treat the underlying cause
   • Correct vitamin D or calcium deficiency
   • Treat coeliac disease or other malabsorption
   • Review steroids and other bone-harming medicines with the prescriber
   • Treat thyroid, parathyroid, cortisol, or sex-hormone disorders
   • Address undernutrition, eating disorder, or menstrual loss
2. Lifestyle and fracture prevention
   • Adequate calcium from food, supplemented only if intake is inadequate
   • Vitamin D if deficient or at risk of deficiency
   • Regular weight-bearing and resistance exercise, tailored to fracture risk
   • Avoid smoking and limit alcohol
   • Maintain a healthy weight and adequate protein/energy intake
   • Avoid high-impact, twisting, or heavy spinal-loading activity if vertebral fractures are present until specialist advice is obtained
3. Medication
   • Medicines are not automatic for young people with low bone density.
   • They may be considered for recurrent fragility fractures, severe osteoporosis, ongoing high-risk steroid treatment, or when the cause cannot be corrected.
   • Options may include bisphosphonates, denosumab, or bone-building medicines such as teriparatide in selected high-risk cases, but selection needs specialist supervision.
   • For anyone who may become pregnant, this discussion is especially important. Some drugs can remain in bone for a long time, and evidence in younger adults is less certain than in postmenopausal osteoporosis.

Practical diagnostic criteria

1. Clinical features of meningitis
   • Acute headache, fever, neck stiffness, photophobia, nausea/vomiting
   • May have malaise or rash
   • Mental status is usually normal or only mildly affected. Prominent confusion, focal deficits, seizures, or reduced consciousness should raise concern for encephalitis or another serious diagnosis.
2. CSF pleocytosis on lumbar puncture
   • CSF white cells >5 cells/mm³ in adults
   • Usually lymphocyte/mononuclear predominant
   • Early viral illness can initially show neutrophil predominance.
3. CSF pattern compatible with aseptic/viral meningitis
   • Opening pressure: normal or mildly raised
   • WBC: usually mild to moderate elevation
   • Protein: normal or mildly elevated
   • Glucose: usually normal, or only minimally reduced
   This typical profile is summarized as mild lymphocytic pleocytosis, mildly raised protein, and normal glucose. Frameworks for Internal Medicine, CSF meningitis profiles, p. 1456-1461.
4. No evidence of pyogenic bacterial meningitis
   • Negative CSF Gram stain
   • Sterile routine bacterial culture, recognizing cultures can become negative after antibiotics
   • No strongly bacterial CSF pattern, such as very high neutrophilic count, markedly low CSF glucose, or markedly elevated CSF lactate
5. Appropriate etiologic testing and exclusion of important alternatives
   • CSF PCR/NAAT, commonly for enteroviruses, HSV-1/2, VZV, and other pathogens based on age, location, immune status, exposure, and season
   • Blood cultures, ideally before antibiotics if bacterial meningitis is possible
   • Targeted testing for tuberculosis, fungi, HIV, syphilis, Lyme disease, etc., when indicated
   • Medication review for drug-induced aseptic meningitis, especially NSAIDs, trimethoprim-sulfamethoxazole, IVIG, some antibiotics, and other agents
   • Consider autoimmune, malignant, and inflammatory causes when infectious studies are unrevealing

Important distinctions

• “Aseptic” does not mean non-infectious. Viral meningitis is the most common cause, but the category also includes partially treated bacterial meningitis, TB/fungal infections, drugs, autoimmune disease, and malignancy.
• Do not label a case aseptic meningitis solely because initial cultures are negative, especially if antibiotics were given before lumbar puncture.
• A normal CSF glucose does not completely exclude bacterial, TB, or fungal meningitis.
• Diagnosis needs integrated interpretation of symptoms, CSF cell count/differential, glucose, protein, Gram stain, culture, PCR, and blood tests. The WHO meningitis guidance states that no individual CSF measurement alone can confirm or exclude meningitis.

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