De acordo com o UpToDate e a aula do medcurso 2023 esse valor é 500, e não 1-2g (esse seria para a utilização de corticoides).

Link: https://www.uptodate.com/contents/iga-nephropathy-clinical-features-and-diagnosis?search=doen%C3%A7a%20de%20berger&source=search_result&selectedTitle=1%7E150&usage_type=default&display_rank=1#H455226641

Trecho do UpToDate:
However, a kidney biopsy may not be indicated in every patient suspected of having IgAN, depending upon their clinical presentation. As an example, a kidney biopsy is not usually performed for patients presenting with isolated hematuria (ie, without evidence of proteinuria or impaired kidney function), since establishing the diagnosis frequently does not alter the course of treatment in such patients. In such patients, a kidney biopsy is usually performed only if there are signs suggestive of more severe or progressive disease, such as persistent proteinuria of at least 500 mg per day or an elevated serum creatinine concentration. Indications for performing a kidney biopsy vary geographically, and in some countries, there is a greater willingness of nephrologists to biopsy patients who have persistent microscopic hematuria with preserved kidney function and without proteinuria. (See "The kidney biopsy", section on 'Appropriate use of kidney biopsy' and "Etiology and evaluation of hematuria in adults", section on 'Role of kidney biopsy'.)