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Background: In addition to its SSTR-specific binding in tumors and healthy tissues, DOTATOC analogues accumulate in kidney parenchyma. Renal tracer uptake might be a surrogate of kidney function or dysfunction. This study aimed to evaluate if kidney function can be estimated from ⁶⁸Ga[Ga]-DOTATOC uptake in PET/CT and its impact on the nephrotoxicity of ¹⁷⁷Lu[Lu]-DOTATOC PRRT. Methods: Two cohorts of patients (A: 128 diagnostic patients; B: 32 PRRT patients) were evaluated retrospectively. SUV values of the kidneys, physiologically SSTR-expressing organs and in background compartments were assessed. Kidney function was calculated as eGFR by CKD-EPI creatinine equation. Pearson’s correlation coefficients and treatment-induced changes of uptake and kidney function were assessed and compared. Results: Kidney function and renal DOTATOC uptake showed a significant inverse correlation (R² = 0.037; <i>p</i> = 0.029). Evaluated models of PET/CT measurements were not able to predict kidney function sufficiently. The uptake of other organs did not depend on eGFR. While the renal uptake increased after PRRT (<i>p</i> < 0.001), the kidney function did not change significantly (<i>p</i> = 0.382). Neither low pre-therapeutic eGFR nor high pre-therapeutic kidney uptake were risk factors of PRRT-induced deterioration in kidney function. Conclusion: The relevance of kidney function for renal ⁶⁸Ga[Ga]-DOTATOC uptake is limited. The nephrotoxicity of ¹⁷⁷Lu[Lu]-DOTATOC PRRT might be low and cannot be reliably predicted by pre-therapeutic measurements.