Final answer:
An apical heart rate of 130 beats/min in a client with hyperthyroidism is the most critical symptom to report, as it may indicate serious cardiovascular issues and risk of thyroid storm.
Step-by-step explanation:
The clinical manifestation in the client with hyperthyroidism that is most important to report to the healthcare provider is an apical heart rate of 130 beats/min. Hyperthyroidism is characterized by an abnormally elevated level of thyroid hormone in the blood, which leads to an array of symptoms due to the increased metabolic rate.
Among the manifestations listed, while nervousness, increased appetite, and insomnia are concerning, a high apical heart rate indicates a potential for more serious cardiovascular issues and should be reported immediately. An apical heart rate significantly above normal can suggest tachycardia, which is often associated with hyperthyroidism and can be a sign of a thyroid storm, a potentially life-threatening condition requiring prompt medical attention.