Table 1 Overview of criteria for referral recommendations

Kidney function

  GFR

eGFR (ml/min)

 < 30 or 30–59 ^b and one of the following criteria

 < 45 or 45–59 and one of the following criteria

 < 30 or 30–59 and one of the following criteria

 < 30 or 30–59 and one of the following criteria

  GFR progression > 5 ml/min / year

mean eGFR reduction > 5 ml/min from first to second follow-up examination

x

  GFR progression > 5 ml/min / year or GFR reduction ≥ 25% / year

mean eGFR reduction > 5 ml/min from first to second follow-up examination or mean eGFR reduction of ≥ 25%

x

  GFR progression ≥ 15 ml/ min / year or GFR reduction ≥ 25% / year

mean eGFR reduction > 15 ml/min from first to second follow-up examination or mean eGFR reduction of ≥ 25%

x

Hypertension refractory to treatment

  BP > 150 and/or > 90 mmHg and ≥ 3 antihypertensives

BP: mean systolic BP of 2. and 3. measurement

Antihypertensives: ATC-codes C02-C09

x

x

  BP > 150 and/or > 90 mmHg and ≥ 4 antihypertensives

BP: mean systolic BP of 2. and 3. measurement

Antihypertensives: ATC-codes C02-C09

x

x

Proteinuria

  Proteinuria > 200 mg/l, subjects with diabetes: > 20 mg/l

Urine albumin dipstick category, subjects with diabetes: urine protein dipstick category

x

  Albuminuria ≥ 300 mg/g or ≥ 30 mg/mmol

ACR

x

  Proteinuria ≥ 70 mg/mmol and non-diabetic

ACR

x

  Albuminuria ≥ 30 mg/g or ≥ 3 mg/mmol

ACR

x

  ACR ≥ 30 mg/mmol and haematuria

ACR and urine dipstick category red blood cells +  + 

x

Haematuria

  Micro- or macrohematuria

urine dipstick category red blood cells +  + ^a

x

x

  Haematuria without known urologic cause

urine dipstick category red blood cells +  + ^a

x

Morphologic and structural kidney abnormalities

  Morphologic kidney changes

ICD-10-GM codes

• at least one billing code one year prior to study examination of second follow-up (N02.-, N20.-)

• at least one billing code five years prior to study examination of second follow-up (N11.-, N13.-, N26.-, N28.-, C64.-, D41.0, Q61.-, Q63.-, I70.1)

x

  Kidney stones

ICD-10-GM codes N20.-, at least one billing code one year prior to study examination of second follow-up

x

  Renal artery stenosis

ICD-10-GM code I70.1, at least one billing code five years prior to study examination of second follow-up

x

Miscellaneous

  Hypocalcaemia

 < 2.12 mmol/l

x

  Hyperphosphatemia

 > 1.6 mmol/l

x

  Abnormalities of serum potassium

Serum potassium < 3.7 mmol/l or > 5.1 mmol/l

x

Inherited kidney disease

ICD-10-GM codes, at least one billing code five years prior to study examination of second follow-up (Q61.-, Q63.-)

x

x

Anaemia

WHO reference values haemoglobin, female: < 7.4 mmol/l, male: < 8.1 mmol/l

x