J Med Cases

Journal of Medical Cases, ISSN 1923-4155 print, 1923-4163 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Med Cases and Elmer Press Inc

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Case Report

Volume 17, Number 3, March 2026, pages 133-139

Hypophosphatemic Osteomalacia Induced by Low-Dose Adefovir-Related Fanconi Syndrome

↓ Figure 1. Whole-body bone scintigraphy showing multiple areas of increased radiotracer uptake involving the anterior arcs of the right third and seventh ribs, the posterior arcs of the right sixth and 11th ribs, the anterolateral and posterior arcs of the left third through sixth ribs, the C5–T1 spine, the left calcaneus, the right midfoot, and the lower sacral region.

↓ **Table 1.** Laboratory Values at the Initial Presentation to the Endocrinology Department and During Follow-Up
Laboratory test (reference range)	Initial	3 mo	6 mo	1 yr	2 yr	3 yr
^aAbnormal values. 3 mo: 3 months; 6 mo: 6 months; 1 yr: 1 year; 2 yr: 2 years; 3 yr: 3 years; BMD: bone mineral density; DXA: dual-energy X-ray absorptiometry.
Serum
Calcium (8.6–10.2 mg/dL)	9.1	9.2	9.8	9.2	9.3	9.3
Albumin (3.5–5.2 g/dL)	5.3	4.5	5.1	4.8	4.9	4.6
Corrected calcium (8.6–10.2 mg/dL)	8.1^a	8.8	8.9	8.6	8.6	8.8
Phosphorus (2.5–4.5 mg/dL)	1.8^a	2.8	3.1	2.86	3.2	3.1
Alkaline phosphatase (40–129 U/L)	308^a	419^a	283^a	193^a	109	105
Creatinine (0.67–1.17 mg/dL)	1.31^a	1.23^a	1.33^a	1.26^a	1.22^a	1.14
Estimated glomerular filtration rate (mL/min/1.73 m²)	60	64	58	62	67	73
Fasting glucose (70–99 mg/dL)	138^a		148^a	125^a	117^a	136^a
Hemoglobin A1c (%)			6.1^a	6.2^a	6.4^a	6.9^a
Uric acid (3.4–7.0 mg/dL)	1.8^a		2.7^a	2.8^a	3.1^a	2.8^a
Intact parathyroid hormone (8–76 pg/mL)	14.4		12.8	12.8	12.1	13
25-hydroxyvitamin D (ng/mL)	21.7^a		31.4	34.5	31.7	34.8
1,25-dihydroxyvitamin D (19.6–54.3 pg/mL)	47.35		81.49^a	82.99^a	76.68^a	78.97^a
Magnesium (1.6–2.4 mg/dL)	2.44^a			2.41^a	2.28	2.29
Aspartate aminotransferase (0–40 IU/L)	15		18	17	25	19
Alanine aminotransferase (0–40 IU/L)	14		20	16	24	19
Sodium (136–145 mmol/L)	138	139	139	138	138	136
Potassium (3.5–5.1 mmol/L)	4.4	4.5	4.5	4.3	4.3	4.1
Chloride (98–107 mmol/L)	105	105	104	104	104	103
Urine analysis
Protein	2+^a			1+^a	1+^a	1+^a
Glucose	3+^a			3+^a	3+^a	3+^a
24-h urine laboratory
Protein (0–150 mg/day)	58
Calcium (100–300 mg/day)	328
Phosphorus (0.4–1.3 g/day)	0.95
Creatinine (1.04–2.35 g/day)	1.05
Tubular reabsorption of phosphorus (85–95%)	34^a
Spot urine
Microalbumin (mg/dL)				11.2	12.3	10.4
Calcium (mg/dL)				35.7	30.6	21.1
Phosphorus (mg/dL)				69.28	78.6	58.6
Creatinine (39–259 mg/dL)				119.7	117.2	87.6
Microalbumin/creatinine ratio (mg/g)				94^a	104^a	119^a
Calcium/creatinine clearance ratio				0.04	0.037	0.029
Tubular reabsorption of phosphorus (85–95%)				74.4^a	74^a	75.4^a
BMD by DXA measurement, T-score
Lumbar spine (L1–4)	–2.4^a			–1.1^a		–0.9
Femoral neck	–2.3^a			–1.4^a		–1
Total hip	–2.2^a			–0.7		–0.5

↓ Table 1. Laboratory Values at the Initial Presentation to the Endocrinology Department and During Follow-Up

Laboratory test (reference range)

Initial

3 mo

6 mo

1 yr

2 yr

3 yr

^aAbnormal values. 3 mo: 3 months; 6 mo: 6 months; 1 yr: 1 year; 2 yr: 2 years; 3 yr: 3 years; BMD: bone mineral density; DXA: dual-energy X-ray absorptiometry.

Serum

Calcium (8.6–10.2 mg/dL)

9.1

9.2

9.8

9.2

9.3

Albumin (3.5–5.2 g/dL)

5.3

4.5

5.1

4.8

4.9

4.6

Corrected calcium (8.6–10.2 mg/dL)

8.1^a

8.8

8.9

8.6

8.8

Phosphorus (2.5–4.5 mg/dL)

1.8^a

2.8

3.1

2.86

3.2

3.1

Alkaline phosphatase (40–129 U/L)

308^a

419^a

283^a

193^a

109

105

Creatinine (0.67–1.17 mg/dL)

1.31^a

1.23^a

1.33^a

1.26^a

1.22^a

1.14

Estimated glomerular filtration rate (mL/min/1.73 m²)

Fasting glucose (70–99 mg/dL)

138^a

148^a

125^a

117^a

136^a

Hemoglobin A1c (%)

6.1^a

6.2^a

6.4^a

6.9^a

Uric acid (3.4–7.0 mg/dL)

1.8^a

2.7^a

2.8^a

3.1^a

2.8^a

Intact parathyroid hormone (8–76 pg/mL)

14.4

12.8

12.1

25-hydroxyvitamin D (ng/mL)

21.7^a

31.4

34.5

31.7

34.8

1,25-dihydroxyvitamin D (19.6–54.3 pg/mL)

47.35

81.49^a

82.99^a

76.68^a

78.97^a

Magnesium (1.6–2.4 mg/dL)

2.44^a

2.41^a

2.28

2.29

Aspartate aminotransferase (0–40 IU/L)

Alanine aminotransferase (0–40 IU/L)

Sodium (136–145 mmol/L)

138

139

138

136

Potassium (3.5–5.1 mmol/L)

4.4

4.5

4.3

4.1

Chloride (98–107 mmol/L)

105

104

103

Urine analysis

Protein

2+^a

1+^a

Glucose

3+^a

24-h urine laboratory

Protein (0–150 mg/day)

Calcium (100–300 mg/day)

328

Phosphorus (0.4–1.3 g/day)

0.95

Creatinine (1.04–2.35 g/day)

1.05

Tubular reabsorption of phosphorus (85–95%)

34^a

Spot urine

Microalbumin (mg/dL)

11.2

12.3

10.4

Calcium (mg/dL)

35.7

30.6

21.1

Phosphorus (mg/dL)

69.28

78.6

58.6

Creatinine (39–259 mg/dL)

119.7

117.2

87.6

Microalbumin/creatinine ratio (mg/g)

94^a

104^a

119^a

Calcium/creatinine clearance ratio

0.04

0.037

0.029

Tubular reabsorption of phosphorus (85–95%)

74.4^a

74^a

75.4^a

BMD by DXA measurement, T-score

Lumbar spine (L1–4)

–2.4^a

–1.1^a

–0.9

Femoral neck

–2.3^a

–1.4^a

–1

Total hip

–2.2^a

–0.7

–0.5