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 14, Number 9-10, October 2023, pages 344-349

Improvement in Tubulointerstitial Nephritis With Glucocorticoid Therapy in an Anorexia Nervosa Patient

Figure 1. Computed tomography imaging findings. There is no renal atrophy and no kidney stones. (a) Right kidney. (b) Left kidney.

Figure 2. The clinical course of the patient. eGFR: estimated glomerular filtration rate, HCO₃^-: bicarbonate, K: potassium, mPSL: methylprednisolone, PSL: prednisolone.

Figure 3. Renal pathology findings. (a, b) The tubulointerstitium showed diffuse inflammatory cell infiltration and fibrocellular change. (a) Periodic acid-Schiff staining × 100. (b) Masson’s trichrome stain × 100. (c) The glomerulus showed no cellular lesion or global sclerosis (periodic acid-Schiff staining × 200). (d) Inflammatory cells in the tubulointerstitium were mainly lymphocytes and plasma cells, and tubulitis was observed (hematoxylin and eosin stain × 400).

**Table 1.** Laboratory Findings
Laboratory test	Value	Reference range
ACE: angiotensin-converting enzyme; Alb: albumin; ANA: antinuclear antibodies; BUN: blood urea nitrogen; Ca: calcium; CH50: hemolytic unit of complement; Cl: chlorine; Cr: creatinine; CRP: C-reactive protein; C3: complement component 3; C4: complement component 4; ds-DNA: double-stranded deoxyribonucleic acid; eGFR: estimated glomerular filtration rate; HCO₃^-: bicarbonate; K: potassium; Na: natremia; NAG: N-acetylglucosaminidase; pCO₂: partial pressure of carbon dioxide; pH: potential of hydrogen; Plt: platelet; RBC: red blood cell; Sm: Smith; SS-A: Sjogren’s syndrome antigen A; SS-B: Sjogren’s syndrome antigen B; TP: total protein; WBC: white blood cell; β2MG: β2-microglobulin.
WBC (/µL)	4,300	3,300 - 8,600
Hb (g/dL)	5.8	13.7 - 16.8
Plt (/µL)	357,000	158,000 - 34,8000
TP (g/dL)	7.5	6.6 - 8.1
Alb (g/dL)	4.3	4.1 - 5.1
BUN (mg/dL)	31	8 - 20
Cr (mg/dL)	5.01	0.65 - 1.07
eGFR (mL/min/1.73 m²)	8.72	> 60
Na (mEq/L)	136	138 - 145
K (mEq/L)	2.1	3.6 - 4.8
Cl (mEq/L)	70	101 - 108
Ca (mg/dL)	9.0	8.8 - 10.1
CRP (mg/dL)	0.01	0.00 - 0.14
ANA	160 (speckled)	Negative
SS-A antibody (U/mL)	< 10	Negative
SS-B antibody (U/mL)	< 10	Negative
ds-DNA antibody (IU/mL)	< 10	Negative
Sm antibody (U/mL)	< 1	Negative
C3 (mg/dL)	51.7	73 - 183
C4 (mg/dL)	2.3	11 - 31
CH50 (CH50/mL)	Undetectable	30 - 46
ACE (IU/L)	8.8	8.3 - 21.4
Venous blood pH	7.479	7.35 - 7.45
Venous blood pCO₂ (mm Hg)	20.8	35 - 45
Venous blood HCO₃^-(mEq/L)	54.2	22 - 26
Urinary red blood cells (/HPF)	1 - 4	< 5
Urinary white blood cells (/HPF)	< 1	< 5
Urinary protein (g/day)	0.22	< 0.15
Urinary NAG (U/L)	20.0	0.7 - 11.2
Urinary β2MG (µg/L)	74,105.7	< 230

Table 1. Laboratory Findings

Laboratory test

Value

Reference range

ACE: angiotensin-converting enzyme; Alb: albumin; ANA: antinuclear antibodies; BUN: blood urea nitrogen; Ca: calcium; CH50: hemolytic unit of complement; Cl: chlorine; Cr: creatinine; CRP: C-reactive protein; C3: complement component 3; C4: complement component 4; ds-DNA: double-stranded deoxyribonucleic acid; eGFR: estimated glomerular filtration rate; HCO₃^-: bicarbonate; K: potassium; Na: natremia; NAG: N-acetylglucosaminidase; pCO₂: partial pressure of carbon dioxide; pH: potential of hydrogen; Plt: platelet; RBC: red blood cell; Sm: Smith; SS-A: Sjogren’s syndrome antigen A; SS-B: Sjogren’s syndrome antigen B; TP: total protein; WBC: white blood cell; β2MG: β2-microglobulin.

WBC (/µL)

4,300

3,300 - 8,600

Hb (g/dL)

5.8

13.7 - 16.8

Plt (/µL)

357,000

158,000 - 34,8000

TP (g/dL)

7.5

6.6 - 8.1

Alb (g/dL)

4.3

4.1 - 5.1

BUN (mg/dL)

8 - 20

Cr (mg/dL)

5.01

0.65 - 1.07

eGFR (mL/min/1.73 m²)

8.72

> 60

Na (mEq/L)

136

138 - 145

K (mEq/L)

2.1

3.6 - 4.8

Cl (mEq/L)

101 - 108

Ca (mg/dL)

9.0

8.8 - 10.1

CRP (mg/dL)

0.01

0.00 - 0.14

ANA

160 (speckled)

Negative

SS-A antibody (U/mL)

< 10

Negative

SS-B antibody (U/mL)

< 10

Negative

ds-DNA antibody (IU/mL)

< 10

Negative

Sm antibody (U/mL)

< 1

Negative

C3 (mg/dL)

51.7

73 - 183

C4 (mg/dL)

2.3

11 - 31

CH50 (CH50/mL)

Undetectable

30 - 46

ACE (IU/L)

8.8

8.3 - 21.4

Venous blood pH

7.479

7.35 - 7.45

Venous blood pCO₂ (mm Hg)

20.8

35 - 45

Venous blood HCO₃^-(mEq/L)

54.2

22 - 26

Urinary red blood cells (/HPF)

1 - 4

< 5

Urinary white blood cells (/HPF)

< 1

< 5

Urinary protein (g/day)

0.22

< 0.15

Urinary NAG (U/L)

20.0

0.7 - 11.2

Urinary β2MG (µg/L)

74,105.7

< 230