Table 5.

Recommendations for the follow-up of patients with XLH rickets receiving conventional treatment [4, 25]

Clinical assessment	Timing
Clinical and auxological examination	< 5 years:1–3 months > 5 years: 3–6 months
Dental Examination	Every 6–12 months or based on clinical symptoms
Orthopedic examination	Every 12 months or based on clinical symptoms
Hearing test	>8 years or based on clinical symptoms
Biochemical parameters
aSerum calcium, inorganic phosphate, creatinine, alkaline phosphatase, PTH	Every 3–6 months
Urinary calcium creatinine ratio, bTmP/GFR	Every 3–6 months in patients on active vitamin D or Burosumab treatment
Imaging examinations
Radiographs of wrists, knees, standing lower limbs	Every 1–2 years or based on clinical signs
Renal ultrasonography	Every year
Fundoscopy and brain MRI	In the presence of craniosynostosis or skull shape malformation, headache, neurological symptoms or visual disturbances.
Quality of life	Every year

^aBiochemical parameters including serum phosphate, ALP and TmP/GFR must be interpreted with age-specific normative value

^bTmP/GFR is the maximum rate of tubular reabsorption of phosphate per glomerular filtration rate; calculated by entering the fasting urine and plasma concentrations (same unit) into following equation: TmP/GFR = [25]

Age specific upper normal range of TmP/GFR: 2.2 (< 1 year), 1.4 (1–3 years), 1.1 (3–5 years), 0.8 (5–7 years), 0.7 (> 7 years)