It is important clinical to distinguish between muscle weakness, fatigue, and asthenia. Fatigue describes the inability to continue performing a task after multiple repetitions; in contrast, a patient with primary weakness is unable to perform the first repetition of the task. Asthenia is a sense of weariness or exhaustion in the absence of muscle weakness. Conditions that result in intrinsic muscle weakness can be divided into several main categories: infectious, neurologic, endocrine, inflammatory, rheumatologic, genetic, metabolic, electrolyte-induced, or drug-induced.

HP:0008979, HP:0009061, HP:0002309, HP:0009012

human_phenotype

HP:0001324