Preheat the oven to 375?F (190?C) and line a muffin tin with paper liners.

In a large bowl, whisk together the flour, baking powder, baking soda, salt, and sugar.

In another bowl, mix the melted butter, buttermilk, eggs, lemon zest, and lemon juice until well combined.

Pour the wet ingredients into the dry ingredients and stir until just combined.

Gently fold in the blueberries.

Divide the batter evenly among the muffin cups, filling each about 2/3 full.

Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean.

Allow the muffins to cool in the pan for 5 minutes, then transfer to a cooling rack.